Abstract
The genus Gonioctena is recorded for the first time in Sicily, and Gonioctena theae n. sp. from Nebrodi Mountain is described. The new species belongs to the subgenus Spartoxena Motschulsky, 1860. Its body is slightly prolonged, weakly convex with wide pronotum, slightly convex with four setiferous pores at each angle. Elytra shows nine striae of irregular punctures. Its morphological and ecological characteristics were never recorded thus far for the known species of the genus.
Keywords:
Introduction
Recent studies on the Coleoptera of Sicily (Baviera & Sparacio Citation2002; Magrini & Baviera Citation2003; Liberti & Baviera Citation2004; Pesarini & Baviera Citation2006) led to a research project by the University of Messina focused on Coleoptera diversity in protected environments of Messina Province. The present study is part of this project. During periodic samplings in Nebrodi Park, several specimens of a coleopteran belonging to the genus Gonioctena Chevrolat in Dejean, 1837 (Coleoptera Chrysomelidae, Chrysomelinae), never recorded in Sicily, were collected near Maulazzo Lake at 1400 m above sea level.
According to Daccordi (Citation1994), the genus Gonioctena includes 11 subgenera and 84 species distributed in the Holarctic and Oriental Regions. No species of Gonioctena is currently known from Neotropical and Afrotropical Regions, which instead contain six species of the closely related genus Centroscelis Vogel, 1871. In Australia, some species of the genus Faex Weise, 1901 show affinities with Oriental species of Gonioctena. Currently 13 species of Gonioctena are listed from Italy (Biondi et al. Citation1994), including Gonioctena (Spartomena) fornicata (Brüggemann, 1873), a south‐eastern European pest of alpha‐alpha accidentally introduced in 1953 (Daccordi et al. Citation1991).
All Gonioctena species are oligophagous or monophagous, feeding on plants belonging to the following families: Fabaceae, Sambucaceae, Ulmaceae, Betulaceae, Corylaceae, Carpinaceae, Fagaceae, Rosaceae, Salicaceae (Jolivet & Hawkeswood Citation1995).
The specimens collected belong to a new species of Gonioctena, described in the present note.
Materials and methods
All the specimens were collected by a beating tray, and glued on entomological label. When extracted, the genital apparatus was soaked in cold dilute KOH, and glued on another label mounted on the same pin of the specimen from which it was extracted. Photomicrographs and drawings were made using a Wild M5 stereo‐microscope associated with a camera lucida. SEM micrographs were made using Jeol JSM‐5610LV scanning electron microscope.
Taxonomic accounts
The genus Gonioctena occupies a well‐defined position within the Chrysomelinae of the subtribe Paropsina. The main characters distinguishing the genus are: presence of a tooth on mid and hind tibiae, a more or less deep impression on external side of mandibles (which housing last article of palpi) and appendiculate tarsal claws. The closest genus is Machomena Dubois, 1887, a monospecific taxon endemic to Sardinia and Corsica, which is distinguished by the extremely specialized structure of the median lobe of aedeagus and by simple claws (Daccordi et al. Citation1991).
Gonioctena (Spartoxena) theae n. sp.
Type series
1 ♂ holotypus, Italy, Sicily, Messina, Nebrodi Mountains, Maulazzo Lake, 1400m a.s.l., 26.V.2004, C. Baviera leg., MSNG.
Paratypi: 9 ♂♂ and 6 ♀♀ idem (MSNG, MSNM, MZC, CL, CB, CD); 1 ♀ idem, 31.V.2003, leg. C. Baviera, (CB); 9 ♂♂ 6 ♀♀, idem, 14.V.2004, leg. Baviera C., (CB,CD,CS); 2 ♂♂, 2 ♀♀, idem, 13.V.2005, leg. Baviera C., (CB); 1♂, 1 ♀, idem, 02.VII.2005, leg. Baviera C., (CB); 11 ♂♂, 5 ♀♀ 26.V.2006, leg. Baviera C., (CB, CD, CS); 18 ♂♂, 7 ♀♀, idem, 26.V.2006, leg. Daccordi M. (CD, MSNV, CJB, CEP, NHM, MSNH).
Type specimens will be preserved in the following collections:
CB: Coll. C. Baviera (Messina); CD: Coll. M. Daccordi (Verona); CS: Coll. D. Sassi (Castelmarte) CL: Coll. R. Lisa (Firenze); MSNG: Coll. Civic Museum of Natural History "G. Doria" (Genova); MSNM: Coll. Civic Museum of Natural History Milan; MZC: Coll. Zoological Museum “Cambria” (Messina); MSNV: Coll. Civic Museum of Natural History Verona; CJB: Coll. Jean Claude Bourdonné (Lesparrou France); CEP: Coll. Eduard Petitpierre (Palma de Mallorca, Spain); NHM: Coll. Natural History Museum London.
Diagnosis
Body slightly prolonged, weakly convex; pronotum wide, slightly convex with four setiferous pores at each angle; humeral callus marked; elytra with nine striae of punctures that are somewhat irregular and often fused, particularly on lateral sides; appendiculate tarsal claws.
Description of holotype
Length: 6.2 mm, width: 3.6 mm. Body slightly prolonged, weakly convex. Elytra and scutellum neutral orange; same colour for basal six segments of antenna, lateral sides of head, labial and maxillar palps (pars), mandible (pars), labrum, frons on its vertex and near compound eyes, distal apex of femora, trochanters, posterior margin of abdominal segments, tarsi (pars); an orange undertone also present on lateral edge of pronotum. Apical five segments of antennae, frons, maxillary palp (pars), mandibular apex, legs, ventral side and most of pronotum blackish. Three blackish spots on each elytron: an anterior one between humeral callus and scutellum, a second one (semilunar shape) near the middle of the elytron, and a third one near middle of elytral suture (Figure ).
Figure 1 Gonioctena theae n. sp., Holotypus ♂. A, habitus; B, median lobe of aedeagus, ventral view; C, median lobe of aedeagus, dorsal view; D, median lobe of aedeagus, left lateral view; E, elytral punctuation in the anterior third half of the right elytron. Gonioctena theae n. sp.; F, larva on Crataegus monogyna Jacq.
Frons wide with double punctures denser near eye margins; antennal toruli weakly raised. Clypeus separated from frons by a wide V‐shaped line, with scattered punctures mixed with smaller denser ones. Antennae slightly longer than posterior margin of thorax, with slender segments that becoming wider starting from sixth, (Figure ). Labrum narrow, distal margin deeply curved with a curved row of setigerous punctures. Mandible sub‐square with sunken external margins. Last segment of maxillary palpi slightly widened (Figure ).
Figure 2 Gonioctena theae n. sp., Holotypus ♂: A, left antenna; B, maxillary palp; C, fore right tibia; D, mid right tibia and tarsus; E, fore right tarsus; F, tarsal claw. Gonioctena theae n. sp., Paratypus ♀: G, fore right tarsus; H, maxillary palp; I, left antenna.
Thorax weakly convex, wider than long (1.3 mm length ×0.3 mm width), with fairly dense punctures (on disc, distance between punctures 1–2 times greater than puncture diameter); some wider punctures mixed with smaller ones becoming closer towards margins; anterior and posterior angles with setigerous punctures; lateral margin weakly curved; anterior margin widely curved, posterior margin with lateral sides not bordered and sub‐sinuate.
Elytra slightly prolonged, weakly convex, shiny, bright, with nine striae of punctures well separated only on disc, fused on lateral sides, with small punctures between striae (Figure ); in posterior quarter, surface of elytron slightly wrinkled; epipleura flat, slightly widened, without setigerous punctures; humeral calli external not delimited by grooves, with scattered very fine punctures; scutellum wide, rounded, with scattered fine micropunctures. Metathoracic wings well developed. Episterna slightly raised, surface slightly wrinkled and with short thin impressions. Prosternal process wide, raised, bordered at sides, sinuate between femora then widened. Mesosternum bordered between mid femora with large equally spaced punctures at sides, slightly raised posteriorly. Mesoepisterna with sparse punctures; metaepisterna without grooves, with dense large punctures; metaepimera smooth. First abdominal segment not bordered between hind coxae; segments 2–4 wide, punctate, with slightly arcuate posterior margin. Pygidium wide, silky, with wide light median impression.
Legs strong, short, with femora not very wide, subequal; fore tibiae with a quite small tooth on external margin (Figure ), mid and hind tibiae with a large sharp tooth (Figure ); tarsomeres sub‐equal, 1st tarsal segment not notched on its apical margin, slightly padded; onychium protruding beyond margin of 3rd segment, which entired (Figure ). Tarsal claws appendiculate (Figure ).
Median lobe of aedeagus strong, well sclerotized, sinuous, not fissured at the base, with a crista on ventral side; apex fissured, widened into two asymmetrical parts (Figure ); flagellum sclerotized, sinuous, long, blackish, sharply bent in apical part, with a short awl‐shaped appendix at base.
Description of females and variability
Females are distinguished from males by their slightly larger size, antennae shorter (Figure ); last segment of maxillary palp more slender (Figure ); tarsomeres weakly enlarged (Figure ). Spermatheca is absent.
Paratypes vary slightly in the number and size of the blackish spots on elytra, which may even be completely absent (one paratype is monochromatic orange). Rarely, black spots widened and fuse, almost forming bands. Thorax and frons occasionally completely orange and, in some specimens, this colouration extends onto the sides of the thorax, almost entirely involving the ventral parts. Living specimens present bright colouration, varying from brick red to rust or crimson.
Average dimensions measured on 20 specimens (10 ♂♂ and 10 ♀♀): ♂♂ length = 6.4, width = 3.7; ♀♀ length = 6.7, width = 4.0.
Etymology
The new species is dedicated to my mother Thea, who introduced me to the study of natural sciences and the extraordinary diversity of the world of insects.
Comparative notes
On first examination, the size, brightness of the teguments and wide flattened pronotum suggest the attribution of G. theae n. sp. to the G. viminalis‐rufipes group (sensu Daccordi Citation1994). However, because of the shape of elytral punctures, setiferous punctures at the anterior and posterior angles of the pronotum, and the barely perceptible tooth on the anterior tibiae, the new species should be referred to the subgenus Spartoxena. Species belonging to this subgenus have been studied by Boudonné and Doguet (Citation1979) and by Kippenberg (Citation2001), to which the reader is referred for comparisons with G. theae n. sp.
Ecology and biogeography
Larvae (Figure ) and adults of G. theae n. sp. were observed and collected only on some isolated plants of Crataegus monogyna Jacq. in glades of a Quercus cerris L. forest near Maulazzo Lake at approximately 1400 m a.s.l.
The species of the subgenus Spartoxena have a strict western Mediterranean distribution, with the exception of Gonioctena gobanzi Reitter, 1902 whose range reaches south‐western Europe, where it occurs in xeric mountain environments on Cytisanthus radiatus (L.). The presence of G. theae n. sp. in a wet high‐altitude wooded habitat is also unusual in respect of all other species of the subgenus (except for the above‐mentioned G. gobanzi), which prefer xeric or sub‐desertic low‐altitude environments (North Africa) (Daccordi et al. Citation1991). In view of the strong oligophagy of Gonioctena species, the host plant of the new species is also noteworthy: thus far, no member of the Rosaceae has been recorded for any species belonging to the subgenus Spartoxena.
Regarding the Italian distribution, it is remarkable that the new species is isolated from all other Italian species of Gonioctena. In fact, the genus is rather widely distributed in northern Italy, except for Gonioctena (Goniomena) quinquepunctata (Fabricius, 1787) which extends along the Apennine chain and, albeit more sporadic in the south, reaches the Calabrian–Lucanian Apennines (Daccordi et al. Citation1991).
It is also remarkable that G. theae n. sp. is morphologically fairly dissimilar to any of the species of Spartoxena described thus far.
Therefore, the morphological characters, the extremely limited distribution, the isolation from the other congeneric species, the peculiar ecological characteristics and the host plant suggest that the new species could be consider as a noteworthy endemic species, like G. gobanzi (Daccordi et al. Citation1991).
Because of its morphological and bioecological characteristics, and its limited occurrence in a small wet mountain site in north‐eastern Sicily, G. theae n. sp. is a taxon which should be afforded special protection actions in Nebrodi Park management.
Acknowledgements
I am indebted to Mauro Daccordi (Verona, Italy) for his support and guidance in all phases of the present study. I am also thankfully to Michele Zilioli of Civic Natural History Museum of Milan for S.E.M. photos, Gianfranco Curletti of Carmagnola Museum for photo of habitus.
References
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