Advanced search
Publication Cover
The European Zoological Journal Volume 91, 2024 - Issue 1
Submit an article Journal homepage
98
Views
0
CrossRef citations to date
0
Altmetric
Research Article

The subgenus Oligonychus (Oligonychus) Berlese (Acari, Prostigmata, Tetranychidae), diagnostic keys to world species, and taxonomic notes

H. M. S. MushtaqDepartment of Plant Protection, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi ArabiaORCID Iconhttps://orcid.org/0000-0002-6678-4325View further author information
ORCID Icon,
M. KamranDepartment of Plant Protection, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi ArabiaView further author information
&
F. J. AlatawiDepartment of Plant Protection, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi ArabiaCorrespondence[email protected]
ORCID Iconhttps://orcid.org/0000-0002-6824-2650View further author information
ORCID Icon
Pages 559-567 | Received 30 Aug 2023, Accepted 28 Apr 2024, Published online: 28 May 2024

Abstract

The present study provides the morphotaxonomic-based identification of the world species of the subgenus Oligonychus (Oligonychus) Berlese. In this lieu, five diagnostic keys were erected to identify Oligonychus (O.) species belonging to five subgroups; smithi, peruvianus, subnudus, aceris, and coffeae. In addition, taxonomic notes on some Oligonychus (O.) species, either briefly described or closely related, were provided, and intraspecific variations were highlighted.

1. Introduction

Oligonychus Berlese (Acari, Prostigmata, Tetranychidae) is one of the economically important and the largest genus, comprising of 211 species (including 17 ungrouped species) of spider mites, divided into two subgenera, i.e., Oligonychus Berlese (74 species, excluding two recently synonymized species) and Reckiella Tuttle and Baker (120 species) (Mushtaq et al. Citation2021; Migeon & Dorkeld Citation2022; Mushtaq et al. Citation2023b; Mushtaq, Kamran & Alatawi Citation2023a). Some Oligonychus (O.) species, e.g., O.(O.) coffeae (Neitner), O. (O.) punicae (Hirst), and O. (O.) perseae Tuttle, Baker, & Abbatiello, are polyphagous, widely distributed, and severe pests of various cash crops (Jeppson et al. Citation1975; Migeon & Dorkeld Citation2022).

Accurately identifying Oligonychus species compulsorily requires carefully observing both male and female morphological characteristics (Meyer Citation1987; Ben-David Citation2008; Mushtaq et al. Citation2021). This raises complications in species identification due to morphological similarities in females of several species, intraspecific variations, brief descriptions of some species, presence of doubtful species, the involvement of sibling/cryptic species complexes, minor differences in key traits of male aedeagus and above all, the unavailability of male specimens (Pritchard & Baker Citation1955; Jeppson et al. Citation1975; Meyer Citation1987; Khanjani et al. Citation2018; Li et al. Citation2018; Mushtaq et al. Citation2021,Citation2023b).

In the subgenus Oligonychus (O.), some closely related species are practically indistinguishable due to almost similar aedeagal morphology, minor interspecific differences, or intraspecific variations (Pritchard & Baker Citation1955; Beard et al. Citation2003; Khanjani et al. Citation2018; Li et al. Citation2018; Mushtaq et al. Citation2021). On the other hand, some species can only be differentiated based on the inhabited host plant (Pritchard & Baker Citation1955). Despite the taxonomic division of the subgenus Oligonychus (O.) into two species groups and five subgroups (Mushtaq et al. Citation2021), no comprehensive diagnostic key, other than some regional keys, has been developed yet, to identify world species of the subgenus Oligonychus (O.), e.g. (Pritchard & Baker Citation1955; Meyer Citation1974, Citation1987). However, diagnostic keys have been developed to identify the two subgenera, four species groups, and 11 subgroups of the genus Oligonychus (Mushtaq et al. Citation2021) and for the identification of world species of the subgenus Reckeilla (Mushtaq et al. Citation2023a).

The present study aimed to develop the diagnostic key to each of five species subgroups (viz. aceris, coffeae, peruvianus, smithi, and subnudus) of the subgenus Oligonychus (O.). Brief taxonomic notes on some morphologically closely related species and intraspecific variations in some species are also discussed.

2. Materials and methods

The published morphotaxonomic literature of the 74 species of Oligonychus (O.) was collected using the websites of different research journals, various search engines, and personal contacts with acarologists around the globe. All Oligonychus (O.) literature, i.e., descriptions, redescriptions, illustrations of all 74 species, and regionally prepared identification keys, were critically investigated to develop five dichotomous keys for identifying all Oligonychus (O.) species. Moreover, following Mushtaq et al. (Citation2023b), different aedeagal traits were measured for distinguishing among closely related Oligonychus (O.) species.

3. Results

Family Tetranychidae Donnadieu

Subfamily Tetranychinae Berlese

Tribe Tetranychini Reck

Genus Oligonychus Berlese

Type species. Heteronychus brevipodus Targioni-Tozzetti, 1878: 255.

Diagnosis (based on female and male). As defined by Mushtaq et al. Citation2021).

Subgenus Oligonychus Berlese

Type species. Heteronychus brevipodus Targioni-Tozzetti, 1878: 255.

Diagnosis (based on male). As defined by Mushtaq et al. Citation2021).

3.1. Keys to all known species of the subgenus Oligonychus (66 species, excluding eight briefly described species)

3.1.1. Key to species of the subgroup smithi (2 species)

  • 1. Female with 6 tactile setae on tibia II; ventrally bent portion of aedeagus without forming sigmoid pattern, straight and tapering towards tipO. smithi Karuppuchamy & Mohanasundaram

    - Female with 7 tactile setae on tibia II; ventrally bent portion of aedeagus with strong sigmoid pattern, first bends anteriorly then posteriorly..................................O. bambusae Cromroy

3.1.2. Key to species of the subgroup peruvianus (3 species)

  • 1. Female with 8 and 5 tactile setae on tibia I and II, respectively; ventrally bent part of aedeagus long, forming slight angle with slender and almost straight distal hook……… O. sumatranus Ehara

    - Female with 9 and 6/7 tactile setae on tibia I and II, respectively; ventrally bent part of aedeagus short, with pointed tip..................................... 2

    2. Female with dorsal body setae lanceolate, setae c1, d1 and e1 about half or less than half as long as distance between them, e1 not reaching to bases of f1; striae longitudinal between/anterior to e1 setae.......................O. peruvianus (McGregor)

    - Female with dorsal body setae slender, setae c1 and d1 about three-quarters as long as distance between them, e1 reaching to bases of f1; striae forming inverted V-pattern between d1-f1 setae............................ O. perseae Tuttle et al.

3.1.3. Key to species of the subgroup subnudus (17 species, excluding one briefly described species)

  • 1. Female with 5 tactile setae on tibia I (4 tactile setae on tibia II; one tactile setaproximal to duplex on tarsus I & no tactile on tarsus II; all tarsi short & stubby; ventrally bent part of aedeagus gradually narrowing to a sigmoid tip....... O. cunliffei Pritchard & Baker

    - Female with 6 or 7 tactile setae on tibia I.......... 2

    2. Female with 7 tactile setae on tibia I3

    - Female with 6 tactile setae on tibia I 8

    3. Aedeagus with ventrally bent terminal part equal, sub-equal or longer than dorsal margin of shaft...4

    - Aedeagus with ventrally bent terminal part shorter than dorsal margin of shaft…………..5

    4. Female dorsal hysterosomal setae one-half to two-thirds as long as distance between their bases; aedeagus with ventrally bent terminal part almost equal, sub-equal with dorsal margin of shaft........................................ O. laricis Reeves

    - Female dorsal hysterosomal setae very short, less than half to the distance between their bases; aedeagus with ventrally bent terminal part longer than dorsal margin of shaftO. karamatus (Ehara)

    5. Aedeagus with shaft axis forming acute angle (68°) with axis of ventrally bent terminal part..........O. livschitzi Mitrofanov & Bossenko

    - Aedeagus with shaft axis forming right or obtuse angle with axis of ventrally bent terminal part..6

    6. Female dorsal hysterosomal setae slightly longer, variable in length, dorsocentrally located setae (c1, d1, e1 & f1) gradually increasing in length.........O. boudreauxi Pritchard & Baker

    - Female dorsal hysterosomal setae very short, almost equal/subequal in length, either c2 or c3 slightly longer than other hysterosomal setae……..……..……………………………….7

    7. Female palp spinneret about 3 times as long as wide; 4 to 5 pairs of proximoventral hairs on female empodium I; male with 3 and 2 tactile setae on tarsus I and II, respectively, 3 solenidia proximal to duplex on tarsus IO. hondoensis (Ehara)

    - Female palp spinneret about 1.5 times as long as wide; 3 pairs of proximoventral hairs on female empodium I; male with 4 tactile setae on tarsus I and II, 2 solenidia proximal to duplex on tarsus I………………………........... O. yuae Tseng

    8. Female with 5 tactile setae on tibia II............ 9

    - Female with 4 tactile setae on tibia II11

    9. Female with 4 tactile setae proximal to duplex on tarsus I............O. baipisongis Ma & Yuan

    - Female with 2 tactile setae proximal to duplex on tarsus I.....10

    10. Female with 1 (or more) solenidion on tibia of each leg (I-IV); empodium I with 4 pairs of proximoventral hairsO. yasumatsui Ehara & Wongsiri

    - Female without solenidia on tibia II-IV, except 1 on tibia I; empodium I with 5 pairs of proximoventral hairs......................O. clavatus (Ehara)

    11. Female with some dorsal hysterosomal setae set on tubercles................................................ 12

    - Female with all dorsal hysterosomal setae without tubercles............................................... 13

    12. Female with most dorsal setae set on tubercles, tarsus I with 2 tactile setae proximal to duplex; male with long dorsocentral hysterosomal setae, reaching to/beyond bases of next setae in row..........O. tuberculatus Estebanes & Baker

    - Female with few dorsal setae (marginal hysterosomals d2, e2 and f2) set on tubercles and tarsus I with one tactile seta proximal to duplex; male with short dorsocentral hysterosomal setae, as in female.......O. plumosus Estebanes & Baker

    13. Female with first three dorsocentral hysterosomal setae c1, d1 and e1 successively increasing in length, d1 much longer than c1O. milleri (McGregor)

    - Female with dorsal setae c1, d1 and e1 almost equal/subequal in length14

    14. Female with most dorsal hysterosomal setae comparatively longer, c1 one-half to three-fourths as long as the interval to d1........................O. pityinus Pritchard & Baker

    - Female with most dorsal hysterosomal setae comparatively very short, c1 less than one-half as long as the interval to d1..........................15

    15. Male with 3 tactile setae proximal to duplex on tarsus I.................. O. subnudus (McGregor)

    - Male with 1 tactile seta proximal to duplex on tarsusI..16

    16. Female with anterior pair of propodosomal setae v2 distinctly longer than other dorsal body setae..........................O. pini Tuttle et al.

    - Female with setae v2 normal in length, equal or sub-equal with other dorsal body setaeO. pinaceous Mitrofanov & Bossenko

    O. verduzcoi Estebanes & Baker could not be included in the key to species of the subgroup subnudus due to the unavailability of a detailed description/illustration of male aedeagus.

3.1.4. Key to species of the subgroup aceris (4 species)

  • 1. Female with dorsal opisthosomal setae without tubercles.................O. gambelii Tuttle & Baker

    - Female with dorsal opisthosomal setae with tubercles………………………………2

    2. Female with solenidion more than half the length of dorsal tactile seta on tibia IO.aceris (Shimer)

    - Female with solenidion less than half the length of dorsal tactile seta on tibiaI...............................3

    3. Female with 6 pairs of proximoventral hairs on empodium I; male with bent part of aedeagus abruptly narrowed at distal endO. pustulosus Ehara

    - Female with 3 to 4 pairs of proximoventral hairs on empodium I; male with bent part of aedeagus gradually narrowed distallyO. endytus Pritchard & Baker

3.1.5. Key to species of the subgroup coffeae (40 species, excluding three briefly described species)

  • 1. Aedeagus with bent part abruptly expands distally to form small but distinct knob (female tarsus I with 4 tactile setae proximal to proximal duplex)..... O. steinhaueri Flechtmann & Baker

    - Aedeagus with bent part gradually or abruptly narrowing distally to form truncate, rounded, finger-like or sigmoid tip, distally......................... 2

    2. Dorsal margin of aedeagus shaft with deep or shallow notch near base (female with tarsus I and II each with 2 tactile setae ventrally in line or just beyond of duplex; three tactile setae proximal to proximal duplex on tarsus I).............................3

    - Dorsal margin of aedeagus shaft without notch near base.4

    3. Dorsal margin of aedeagus shaft with deep and conspicuous notch near base, distal end of aedeagus with blunt tip........ O. perditus Pritchard & Baker

    - Dorsal margin of aedeagus shaft with much shallower and somewhat wider notch near base, distal end of aedeagus with acute tipO. chamaecyparisae Ma & Yuan

    4. Bent aedeagal part more or less undulate, tapering gradually towards tip, forming slightly sigmoid or S-shaped pattern or tip bends posteriorly (height/length of bent aedeagal part about one-fourth to three-fourth the length of shaft dorsal margin)5

    - Bent aedeagal part almost straight, not undulate, gradually or abruptly narrows distally to form an acute/truncate tip, distally directed ventrad orantero-ventrad9

    5. Female tarsus I with 4 tactile setae behind proximal duplex........................... O. qiliaensis Ma & Yuan

    - Female tarsus I with maximum 3 tactile setae behind proximal duplex....................................................6

    6. Female tarsus I with 1 or 2 tactile setae behind proximal duplex; male aedeagus with shaft axis forming acute angle with axis of bent part, height/length of bent part almost three-fourth the length of shaft dorsal margin.............................................O. tsudomei Ehara

    - Female tarsus I with 3 tactile setae behind proximal duplex; male aedeagus with shaft axis forming obtuse/right angle with axis of bent part, height/length of bent part almost one-fourth to two-fourth the length of shaft dorsal margin7

    7. Female palp spinneret about as long as wideO. neocastaneae Arabuli & Gotoh

    - Female palp spinneret about 1.5 to 2.5 times long as compared to width........................................... 8

    8. Female with dorsal body setae shorter, sc1 and c2 not reaching to sc2 and d2, respectively; tarsus II with 3 tactile setae proximal to proximal duplex in female; male aedeagus with shaft axis forming almost right angle with axis of bent part, height/length of bent aedeagal part almost one-fourth the length of shaft dorsal margin..O. gutierrezi Parsi

    - Female with dorsal body setae long, sc1 and c2 reaching beyond sc2 and d2, respectively; tarsus II with 2 tactile setae proximal to proximal duplex in female; male aedeagus with shaft axis forming obtuse angle with axis of bent part, height/length of bent aedeagal part almost two-fourth the length of shaft dorsal margin……………………………. O. hamedaniensis Khanjani et al.

    9. Female palp spinneret > 2 times longer (2.3-4) than its width….………………….. 10

    - Female palp spinneret < 2 times longer than its width……..……………………15

    10. Female palp spinneret about 3 to 4 times longer than its width................................................. 11

    - Female palp spinneret about 2.3 to 2.5 times longer than its width…..………………….13

    11. Female dorsal body setae without tubercles; femur I with 8 and genua I and II with 5 setae in femaleO. metasequoiae Kuang

    - Female dorsal body setae set on small or prominent tubercles; femur I with 7 and genua I and II with 4 setae in female12

    12. Bent aedeagal part about half or less than half the length of shaft dorsal marginO. longiclavatus (Reck)

    - Bent aedeagal part more than half the length of shaft dorsal margin..............O. shojaeii Khanjani et al.

    13. Aedeagus with shaft axis forming obtuse angle with axis of bent part, bent part height/length about half or less than half the length of shaft dorsal margin and shaft width (male/female peritreme hooked)O. ponmanaiensis Karuppuchamy & Mohanasundaram

    - Aedeagus with shaft axis forming an acute angle with axis of bent part, bent part height/length more than half the length of shaft dorsal margin and shaft width14

    14. Female with 3 tactile setae proximal to proximal duplex on tarsus I, four pairs of proximoventral hairs on empodium I..........O. letchworthi Reeves

    - Female with 4 tactile setae proximal to proximal duplex on tarsus I, five pairs of proximoventral hairs on empodium IO. lagodechii Livshits & Mitrofanov

    15. Duplex setae with proximal member of each pair nearly as long as distal member (both in female & male)O. platani McGregor

    - Duplex setae with proximal member of each pair greatly shorter than distal member in female.......16

    16. Female tarsus I with 3 tactile setae proximal to proximal duplex17

    - Female tarsus I with 4 tactile setae proximal to proximal duplex28

    17. Female palp spinneret about 2 times as long as wide (female opisthosoma with V-shaped striae pattern anterior to setae e1; height/length of bent aedeagal part about one-third the length of shaft dorsal margin)O. piceae (Reck)

    - Female palp spinneret about 1 to 1.5 times longer than wide…..………………… 18

    18. Female with setae c1 comparatively short, almost reaching to bases of setae d119

    - Female with setae c1 distinctly longer, reaching beyond bases ofsetae d121

    19. Female with 3 tactile setae proximal to proximal duplex on tarsus II; palp spinneret about 1.5 times longer than wide; striae transverse on dorsal opisthosoma; male with bent part height/length about half the width of shaftO. juniperi Tuttle et al.

    - Female with 2 tactile setae proximal to proximal duplex on tarsus II; palp spinneret about as long as or slightly longer than wide; striae with whorled or V-type pattern between, around or anterior to setae e1 on dorsal opisthosoma; male with bent part height/length about as long as or longer than the shaft width……………………………….20

    20. Female with dorsal body setae on small/prominent tubercles (sometime indistinguishable on mounted specimens); setae c1 as long as distance between c1-c1; male aedeagus with posterior margin of bent part rounded/convex; shaft axis forming acute/right angle with axis of bent partO. ilicis (McGregor)

    - Female with dorsal body setae without tubercles; setae c1 longer than distance between c1-c1; male aedeagus with posterior margin of bent part flat; shaft axis forming obtuse angle with axis of bent partO. newcomeri (McGregor)

    21. Female palp spinneret about 1.5 times longer than wide22

    - Female palp spinneret about as long as wide…………………23

    22. Female with 2 tactile setae proximal to proximal duplex on tarsus II; empodium I with three-four pairs of proximoventral hairs; male aedeagus with shaft axis forming obtuse angle with axis of bent partO. brevipodus (Targioni Tozzetti)

    - Female with 3 tactile setae proximal to duplex on tarsus II; empodium I with five pairs of proximoventral hairs; male aedeagus with shaft axis forming acute/right angle with axis of bent partO. camelliae Ehara & Gotoh

    23. Aedeagus sausage-like, abruptly narrowing distally forming tiny nipple-like tip (shaft axis forming obtuse angle with axis of bent part)O. bicolor (Banks)

    - Aedeagus not sausage-like, gradually or abruptly narrowing distally forming pointed, blunt, finger or nipple-like tip…….….……………………24

    24. Aedeagus with bent part height/length almost half or less than half the width of shaft (female tarsus II with 2 tactile setae proximal to duplex, tarsus IV with 7 tactile setae and 1 solenidion)O. gotohi Ehara

    - Aedeagus with bent part height/length almost equal or more than shaft width25

    25. Aedeagus with shaft axis forming right angle with axis of bent part (male spinneret about 1.5 times longer than wide; female with transverse striae on dorsal opisthosoma)O. mitis Beglyarov & Mitrofanov

    - Aedeagus with shaft axis forming acute or obtuse angle with axis of bent part26

    26. Female with setae h2 as long as setae f1 (female & male stylophore shallowly notched; male tarsus II with 4 tactile setae proximal to duplex)O. penai Rimando

    - Female with setae h2 shorter, almost < three-fourth the length of setae f1……… 27

    27. Aedeagus with bent part directed ventrad or antero-ventrad distally, forming nipple-like or truncate tip (alive female dark-red in color)O.coffeae (Nietner)

    - Aedeagus with bent part directed caudad distally, forming acute or pointed tip (alive female greenish in color)O. viridis (Banks)

    28. Female palp spinneret about 2 times longer than wide (male palp spinneret about 2 to 2.5 times longer than wide; on conifers)29

    - Female palp spinneret about 1 to 1.8 times longer than wide30

    29. Bent part of male aedeagus comparatively shorter, about half the length of shaft dorsal margin, narrows distally to a truncate tipO. judithae Meyer

    - Bent part of male aedeagus comparatively longer, about as long as or slightly longer than shaft dorsal margin, narrows distally to acute tipO. alpinus(McGregor)*

    30. Female peritreme ending in small hook; length of shaft dorsal margin about > 3 times longer than width of shaft (shaft axis forming right angle with axis of bent part, bent aedeagal part ending in truncate tip; on Bambusa sp.)O. viranoplosFlechtmann

    - Female peritreme straight with bulbous end; length of shaft dorsal margin about < 3 times longer than shaft width…..……..……………… 31

    31. Found usually on conifers…………..….………. 32

    - Found usually on other plants33

    32. Aedeagus with bent part short, directed caudoventrally and abruptly truncate at tip (shaft axis forming obtuse angle with axis of bent part)O. coniferarun (McGregor)

    - Aedeagus with bent part long, tapering distally, directed antero-ventrally or ventrallyO. ununguis (Jacobi)

    33. Dorsal margin length of aedeagal shaft > 2.5 (almost three) times the shaft width (shaft axis forming acute/right angle with axis of bent part; male palp spinneret > 2 times longer than wide)O. cubensis (Livshitis)

    - Dorsal margin length of aedeagal shaft < 2.5 times the shaft width34

    34. Bent part height/length of aedeagus about one-fourth the length of shaft dorsal margin (shaft width longer than bent part height/length; female palp spinneret about 1.3 times longer than wide)…………………….O. peronis Pritchard & Baker

    - Bent part height/length of aedeagus about half or more than half the length of shaft dorsal margin...35

    35. Aedeagus with bent part longer, distal half very slender or elongated, slightly flattened, gradually tapering towards tip; bent part height/length >1.3 times longer than shaft widthO. yothersi (McGregor)

    - Aedeagus with bent part comparatively shorter, gradually or abruptly narrowing distally, distal half not slender and flattened; bent part height/length almost equal or shorter than shaft width36

    36. Aedeagal shaft with dorsal and ventral margin not parallel, ventral margin bowed inside, shaft width abruptly narrowed before bending ventrad; bent part gradually tapering to blunt tip (female palp spinneret about 1.2 times longer than wide)O. ochoai Meyer & Vargas

    - Aedeagal shaft with dorsal and ventral margin almost parallel/sub-parallel, shaft width almost remains same or gradually narrows before turning downward37

    37. Female with dorsal opisthosomal striae forming v-shaped pattern between and anterior to e1 setae (male palp spinneret about 2 times as long as wide; alive male and female body color greenish brown)O. castaneae Ehara & Gotoh

    - Female with dorsal opisthosomal striae typically transverse or rarely forming irregular transverse striae pattern between and anterior to e1 setae....38

    38. Female tarsus III with 9 tactile setae; on Bambusa sp. (bent aedeagal part gradually thinning until ending in acute tip)O. santoantoniensis Feres & Flechtmann

    - Female tarsus III with 8 tactile setae; other than Bambusa sp….. (punicae species complex).......O. punicae (Hirst), O. yusti McGregor

O. alpinus (McGregor)* is transferred from the species subgroup aceris to subgroup coffeae. Previously, it was mistakenly placed under the subgroup aceris (Mushtaq et al. Citation2021).

O. buschi (Reck) could not be included in the key to species of the coffeae subgroup due to poor description of male aedeagus.

O. pruni Mitrofanov & Zapletina could not be included in the key to species of the coffeae subgroup due to the unavailability of aedeagus shape/illustration.

O. tshimkenticus Wainstein could not be included in the key to species of the coffeae subgroup due to missing morphological information about the comparative length of members of duplex setae and the number of tactile setae proximal to the proximal duplex on tarsus I in female.

4. Discussion

In the present study, five diagnostic keys are developed for identifying world Oligonychus (O.) species of the five Oligonychus (O.) subgroups (aceris, coffeae, peruvianus, smithi, and subnudus), using both female and male morphological characters. However, among 74 Oligonychus (O.) species, eight species, viz. O. buschi (Reck), O. brevipilosus (Zacher), O. kobachidzei (Reck), O. meifengensis Lo & Ho, O. nuptialis (Zacher), O. pruni Mitrofanov & Zapletina, O. tshimkenticus Wainstein, and O. verduzcoi Estebanes & Baker, could not be included in species-level diagnostic keys due to the unavailability of required female/male morphological information in the published descriptions/re-descriptions (Zacher Citation1932; Reck Citation1947, Citation1953, Citation1956; Pritchard & Baker Citation1955; Wainstein Citation1956; Estebanes & Baker Citation1968; Mitrofanov & Zapletina Citation1973; Tuttle et al. Citation1976; Lo & Ho Citation1989). Among them, O. brevipilosus, O. kobachidzei, O. meifengensis, and O. nuptialis did not even assign to any species group/subgroup of the subgenus Oligonychus due to the lack of required female morphological information. Indeed, O. kobachidzei was considered a species inquirendae (Mushtaq et al. Citation2021).

4.1. Notes on species of the subgroup subnudus

In the species subgroup subnudus, most Oligonychus (O.) species possess more or less similarly shaped aedeagus. In contrast, a few species (O. karamatus, O. laricis, O. milleri, etc.) generally have different aedeagal morphology. In the literature, variations are noticed in key characters of some species described from various geographical localities. For example, O. boudreauxi was described as having seven tactile setae on tibia I in the original description (Pritchard & Baker Citation1955), whereas Baker and Tuttle (Citation1994) illustrated only five tactile setae. For the key preparation, the original description was followed by considering seven tactile setae on tibia I in O. boudreauxi (Pritchard & Baker Citation1955). Likewise, many descriptions/illustrations of O. milleri indicated six tactile setae on female tibia I (Jeppson et al. Citation1975; Pritchard & Baker Citation1955; Reeves Citation1963; Tuttle et al. Citation1976), whereas two illustrations depicted only five tactile setae (McGregor Citation1950; Baker & Tuttle Citation1994). The literature showed six tactile setae on the female tibia I was followed during the key preparation. Furthermore, based on aedeagal illustrations of O. hondoensis (Ehara Citation1954, Citation1962, Citation1999; Baker & Tuttle Citation1994), O. milleri (McGregor Citation1950; Pritchard & Baker Citation1955; Reeves Citation1963; Estebanes & Baker Citation1968; Jeppson et al. Citation1975; Tuttle et al. Citation1976; Baker & Tuttle Citation1994), O. subnudus (McGregor Citation1950; Pritchard & Baker Citation1955; Estebanes & Baker Citation1968; Jeppson et al. Citation1975; Tuttle et al. Citation1976; Tseng Citation1980; Lo & Ho Citation1989; Baker & Tuttle Citation1994), and O. yuae (Lo & Ho Citation1989; Tseng Citation1990), it seems that intraspecific variations are present that raised a question on persistency of aedeagus as a differential character to identify these species.

4.2. Notes on species of the subgroup aceris

In the species subgroup aceris, most Oligonychus (O.) species have similarly shaped aedeagus (Shimer Citation1869; McGregor Citation1936; Pritchard & Baker Citation1955; Ehara Citation1962; Reeves Citation1963; Jeppson et al. Citation1975; Tuttle et al. Citation1976; Baker & Tuttle Citation1994; Ehara Citation1999). The original illustration of O. alpinus drew seven tactile setae on the female tibia I (McGregor Citation1936). In contrast, five tactile setae were shown in the subsequent redescription (Pritchard & Baker Citation1955). Therefore, O. alpinus was mistakenly placed under the subgroup aceris (Mushtaq et al. Citation2021). We transferred O. alpinus to the species subgroup coffeae in the present study.

4.3. Notes on species of the subgroup coffeae

The species subgroup coffeae is very complicated, with many similar species, which are very difficult to distinguish among each other, including some species complexes, e.g., coffeae complex, punicae complex, and ununguis complex (Pritchard & Baker Citation1955; Meyer Citation1987; Ehara & Gotoh Citation2007; Khanjani et al. Citation2018; Mushtaq et al. Citation2021, Citation2023b). Among them, the punicae species complex has been discussed recently using both morphological and molecular data by suggesting O. mangiferus (Rahman & Sapra) and O. vitis Zaher & Shehata as junior synonyms of O. punicae, as well as revealing a cryptic Oligonychus (O.) species (Mushtaq et al. Citation2023b). Furthermore, intraspecific variations were observed in some important morphological traits of a few species (O. perditus, O. castaneae, O. coffeae, O. ununguis, O. bicolor and O. coniferarum), either within a population or among different populations that reported from various geographical localities (McGregor Citation1950; Pritchard & Baker Citation1955; Meyer Citation1974; Jeppson et al. Citation1975; Tseng Citation1990; Baker & Tuttle Citation1994; Gupta & Gupta Citation1994; Smiley & Baker Citation1995; Ehara Citation1999; Uysal et al. Citation2001; Ehara & Gotoh Citation2007; Arabuli & Gotoh Citation2018). For example, the number of tactile setae behind to proximal duplex in females was found to be variable (usually three, rarely four) among and within a population of O. castaneae (Ehara & Gotoh Citation2007) and O. coffeae (Meyer Citation1974), respectively. Whereas the aforementioned tactile setae in O. ununguis are usually four, three were also observed persistently among females of a population (Pritchard & Baker Citation1955). Additionally, various populations of O. coffeae had been described with straight peritreme (not hooked or U-shaped distally) in both males and females from different localities (Meyer Citation1974; Baker & Tuttle Citation1994; Gupta & Gupta Citation1994; Ehara Citation1999). However, one population of O. coffeae reported from Taiwan showed a strongly hooked peritreme in females (Tseng Citation1990). Also, Arabuli and Gotoh (Citation2018) claimed that peritreme is hooked in the Japanese population of O. coffeae.

The shape of the aedeagus was also found to be variable among different populations of some Oligonychus (O.) species, viz. O. bicolor, O. coniferarum, O. perditus, etc. For example, as compared to all other descriptions of O. perditus (Pritchard & Baker Citation1955; Ehara Citation1962; Lo & Ho Citation1989; Li et al. Citation2019), only one population/illustration did not show a notch near the base of the shaft dorsal margin (Tseng Citation1990). Likewise, the aedeagus shape of O. bicolor is different (aedeagus not sausage-like, shaft axis forming an acute angle with the axis of the bent part, bent part gradually narrowing distally) (McGregor Citation1950), as compared to all other described populations (aedeagus sausage like, shaft axis forming an obtuse angle with the axis of the bent part, bent part abruptly narrowing distally) (Pritchard & Baker Citation1955; Meyer & Ryke Citation1959; Reeves Citation1963; Jeppson et al. Citation1975; Lo & Ho Citation1989; Tseng Citation1990; Baker & Tuttle Citation1994). The aedeagal shape of O. coniferarum that was reported/illustrated from Yemen (Smiley & Baker Citation1995) and Turkey (Uysal et al. Citation2001) seems somewhat different (bent part comparatively longer, directed ventrally and shaft axis forming right angle with the axis of bent part) as compared to all other reported populations (bent part short, directed caudoventrally and shaft axis forming obtuse angle with the axis of bent part) (McGregor Citation1950; Pritchard & Baker Citation1955; Jeppson et al. Citation1975; Baker & Tuttle Citation1994; Khanjani et al. Citation2018).

The relative length/width of palp spinneret has been used as an essential key character to distinguish among various Oligonychus species of the subgroup coffeae, e.g (Meyer Citation1987; Khanjani et al. Citation2018). Previously, O. quercifolius Wainstein (spinneret about two times longer than its width) (Wainstein Citation1956) was synonymized with O. longiclavatus (spinneret about four times longer than its width) (Bagdasarian Citation1957) by Reck (Citation1959). In the original description, O. quercifolius was compared and separated from O. longiclavatus based only on the shape of palp spinneret (Wainstein Citation1956). Therefore, Wainstein (Citation1960) did not accept this synonymy and separated O. quercifolius from O. longiclavatus in the key as valid and separate Oligonychus species. However, later authors (Bolland et al. Citation1998; Migeon & Dorkeld Citation2022; Akimov & Zhovnerchuk Citation2010) agreed with the synonymy of O. quercifolius with O. longiclavatus (Reck Citation1959). We suggest following an integrative taxonomic approach using both morphological and molecular data to reconfirm the taxonomic status of O. quercifolius.

5. Conclusions

The present study comprehensively investigated all published morphotaxonomic literature of the subgenus Oligonychus. Five diagnostic keys to identify the world species of the subgenus Oligonychus are developed. It was noticed that some Oligonychus (O.) species are morphologically very similar and hardly separated based on available morphological information. Moreover, taxonomic notes highlighted some closely related species and intraspecific variations depicted in some Oligonychus (O.) species. Therefore, observing multiple specimens of a species from a population or different populations is strongly suggested to authenticate the persistency of a key morphological character. An integrative taxonomic approach is crucial to distinguish among closely related Oligonychus (O.) species or of resolving species complexes in the subgenus Oligonychus.

Acknowledgments

The authors would like to extend their sincere appreciation to the researchers supporting project number (RSPD2024R807), King Saud University, Riyadh, Saudi Arabia. We also thank Dr. Carlos Holger Wenzel Flechtmann (University of São Paulo, Brazil) for his guidance and help in providing us with the complete taxonomic literature of the genus Oligonychus Berlese.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors would like to extend their sincere appreciation to the researchers supporting project number [RSPD2024R807], King Saud University, Riyadh, Saudi Arabia.

References

  • Akimov IA, Zhovnerchuk OV. 2010. Tetranychid mites — pests of the Megalopolis green plantations. Kyiv, Ukarine: National Academy of Sciences of Ukraine, Schmalgausen Institute of Zoology. pp. 1–107.
  • Arabuli T, Gotoh T. 2018. A new species of spider mite, Oligonychus neocastaneae sp. nov. (Acari: Tetranychidae), from Japan. Zootaxa 4378(4):563–572. DOI: 10.11646/zootaxa.4378.4.7
  • Bagdasarian AT. 1957. Tetranychoid mites (superfamily Tetranychoidea). Fauna of the Armenian S.S.R. Yerevan: Akademia Nauk Armenia S.S.R., Zoological Institute.
  • Baker EW, Tuttle DM. 1994. A guide to the spider mites (Tetranychidae) of the United States. USA: Indira Publishing House.
  • Beard JJ, Walter DE, Allsopp PG. 2003. Spider mites of sugarcane in Australia: A review of grass‐feeding Oligonychus Berlese (Acari: Prostigmata: Tetranychidae). Australian Journal of Entomology 42(1):51–78. DOI: 10.1046/j.1440-6055.2003.00326.x
  • Ben-David T. 2008. Molecular characterization of Israel’s spider mites (Acari: Tetranychidae) [Ph.D. dissertation]. Israel: Hebrew University.
  • Bolland HR, Gutierrez J, Flechtmann CHW. 1998. World catalogue of the spider mite family (Acari: Tetranychidae). Leiden, The Netherlands: Brill Academic Publishers.
  • Ehara S. 1954. Two new spider mites parasitic on Japanese conifers. Annotationes Zoologicae Japonenses 27:102–106.
  • Ehara S. 1962. Tetranychoid mites of conifers in Hokkaido. Journal of the Faculty of Sciences, Hokkaido University, Series VI, Zoology 15:157–175.
  • Ehara S. 1999. Revision of the spider mite family Tetranychidae of Japan (Acari, Prostigmata). Species Diversity 4(1):63–141. DOI: 10.12782/specdiv.4.63
  • Ehara S, Gotoh T. 2007. Five species of spider mites (Acari: Prostigmata: Tetranychidae) from Japan with descriptions of two new species. Zootaxa 1646(1):51–58. DOI: 10.11646/zootaxa.1646.1.5
  • Estebanes GML, Baker EW. 1968. Arañas rojas de Mexico (Acarina: Tetranychidae). Anales de la Escuela Nacional de Ciencias Biologicas 15:61–133.
  • Gupta SK, Gupta YN. 1994. A taxonomic review of Indian Tetranychidae (Acari: Prostigmata): With descriptions of new species, re-descriptions of known species, and keys to genera and species. Calcutta, India: Zoological Survey of India.
  • Jeppson LR, Keifer HH, Baker EW. 1975. Mites injurious to economic plants. Berkeley, CA, USA: Univ of California Press.
  • Khanjani M, Khanjani M, Seeman OD. 2018. The spider mites of the genus Oligonychus Berlese (Acari: Tetranychidae) from Iran. Systematic and Applied Acarology 23(2):223–287. DOI: 10.11158/saa.23.2.4
  • Li J, Yi T-C, Guo J-J, Jin DC. 2018. Ontogenetic development and redescription of Oligonychus pratensis (Banks, 1912) (Acari: Tetranychidae). Zootaxa 4486(3):349–375. DOI: 10.11646/zootaxa.4486.3.7
  • Li J, Yi T-C, Guo J-J, Jin D-C. 2019. Redescription of three species of Oligonychus (Acari, Tetranychidae) from China. Systematic and Applied Acarology 24(6):1071–1106. DOI: 10.11158/saa.24.6.10
  • Lo PKC, Ho CC. 1989. The spider mite family Tetranychidae in Taiwan I. The genus Oligonychus. Journal of Taiwan Museum 42(2):59–76.
  • McGregor EA. 1936. Two spinning mites attacking the incense cedar in California. Annals of the Entomological Society of America 29(4):770–775. DOI: 10.1093/aesa/29.4.770
  • McGregor EA. 1950. Mites of the family Tetranychidae. The American Midland Naturalist 44(2):257–420. DOI: 10.2307/2421963
  • Meyer MKPS. 1974. A revision of the Tetranychidae of Africa (Acari) with a key to the genera of the world, entomology memoir. Pretoria, South Africa: Department of Agricultural Technical Services.
  • Meyer MKPS. 1987. African Tetranychidae (Acari: Prostigmata)—with reference to the world genera, Entomology Memoir. Pretoria, South Africa: Department of Agriculture and Water Supply. p. 69.
  • Meyer MKP, Ryke PAJ. 1959. A revision of the spider mites (Acarina: Tetranychidae) of South Africa with descriptions of a new genus and new species. Journal of the Entomological Society of Southern Africa 22(2):330–366.
  • Migeon A, Dorkeld F. 2022. Spider mites web: A comprehensive database for the Tetranychidae. Available: http://www1.montpellier.inra.fr/CBGP/spmweb. Accessed Jan 2023 5; Updated Oct 2022 25.
  • Mitrofanov VI, Zapletina A. 1973. A new species of the genus Oligonychus from Azerbaijan. Doklady Akademii Nauk Azerbaijan SSR 29:50–52.
  • Mushtaq HMS, Alatawi FJ, Kamran M, Flechtmann CHW. 2021. The genus Oligonychus Berlese (Acari, Prostigmata, Tetranychidae): Taxonomic assessment and a key to subgenera, species groups, and subgroups. Zookeys 1079:89. DOI: 10.3897/zookeys.1079.75175
  • Mushtaq HMS, Kamran M, Alatawi FJ. 2023a. World species of the subgenus Oligonychus (Reckiella) Tuttle and Baker (Acari, Prostigmata, Tetranychidae), diagnostic keys, taxonomic notes, and a new species. Scientific Reports 13(1):13392. DOI: 10.1038/s41598-023-40436-7
  • Mushtaq HMS, Kamran M, Saleh AA, Alatawi FJ. 2023b. Evidence for reconsidering the taxonomic status of closely related Oligonychus species in punicae complex (Acari: Prostigmata: Tetranychidae). Insects 14(1):1–16. DOI: 10.3390/insects14010003
  • Pritchard AE, Baker EW. 1955. A revision of the spider mite family Tetranychidae. San Francisco, CA, USA: Pacific Coast Entomological Society.
  • Reck GF. 1947. New species of tetranychid mites from Georgia. (Tetranychidae, Acari). Soobshcheniya Akademii Nauk Gruzinskoi SSR 8:471–475.
  • Reck GF. 1953. Research investigation on the fauna of the Tetranychidae in Georgia. Trudy Instituta Zoologyi Akademyi Nauk Gruzinskoj SSR 11:161–181.
  • Reck GF. 1956. Novye vidy tetranihovyh klescej iz Vostocnoj Gruzii. Trudy Instituta Zoologyi Akademyi Nauk Gruzinskoj SSR 15:5–28.
  • Reck GF. 1959. Opredelitel’ tetranikhovykh kleshchei. Tbilisi: Izvestiya Akademii Nauk Gruz SSR.
  • Reeves R. 1963. Tetranychidae infesting woody plants in New York State, and a life history study of the Elm spider mite, Eotetranychus matthyssei n. sp. Vol. 380. Ithaca, New York: Memoir of the Cornell University Agricultural Experiment Station, New York State College of Agriculture. 1–99.
  • Shimer H. 1869. Descriptions of two acarians bred from white maple (Acer dasycarpum). Transactions of the American Entomological Society 2:319–320. DOI: 10.2307/25076220
  • Smiley RL, Baker EW. 1995. A report on some tetranychid mites (Acari: Prostigmata) from Yemen. International Journal of Acarology 21(3):135–164. DOI: 10.1080/01647959508684055
  • Tseng YH. 1980. Mites associated with the conifers of Taiwan, (1) Tetranychoidea, with a checklist of the world. Journal of Entomology (National Chung Hsien University) 15:145–168.
  • Tseng YH. 1990. A monograph of the mite family Tetranychidae (Acarina: Tronbidiformes) from Taiwan. (Taiwan Museum Special Publication Series; 9). Taipei, Taiwan Republic of China: Taiwan Museum.
  • Tuttle DM, Baker EW, Abbatiello M. 1976. Spider mites of Mexico (Acarina: Tetranychidae). International Journal of Acarology 2(2):1–102. DOI: 10.1080/01647957608683760
  • Uysal C, Çobanoğlu S, Ökten ME. 2001. Determination of Tetranychoidea (Acarina: Prostigmata) species harmful in the park areas of Ankara. Turkish Journal of Entomology 25:147–160.
  • Wainstein BA. 1956. Fauna of tetranychoid mites in South Kazakhstan. Zoologicheskii Zhurnal 35:384–391.
  • Wainstein BA. 1960. Tetranychoid mites of Kazakhstan (with revision of the family). Trudy Nauchno-Issledoniya Institut Zashchita Rastenii Kazakhstan 5:1–276.
  • Zacher F. 1932. Beiträge zur Kenntnis phytophager Milben. Zoologischer Anzeiger 97:177–185.
Download PDF

Related research

People also read lists articles that other readers of this article have read.

Recommended articles lists articles that we recommend and is powered by our AI driven recommendation engine.

Cited by lists all citing articles based on Crossref citations.
Articles with the Crossref icon will open in a new tab.