On the genus Racekiela in Mexico: molecular and morphological description of Racekiela cresciscrystae n. sp.

ABSTRACT

In Mexico, there are currently two known species of Racekiela: R. ryderii and R. montemflumina. Here we describe a new species from high-altitude streams in central and southern Mexico. Racekiela cresciscrystae sp. nov. presents two morphotypes: thick encrusting with raised ridges or lobose outgrowths at the surface and dark green in colour, or lime-green encrustations. The new species as megascleres presents microspined oxeas from 200 to 300 µm long, some centrotylote, or with malformations. Gemmules are spherical with a tri-layered theca, constituted by radially embedded birotules and pseudobirotules. The birotules have longer shaft than the rotule diameter, which is flat, and some slightly umbonate. Pseudobirotules of typical morphology have strongly or somewhat spined shaft. Spines can be straight or hooked. The species also presents other type of pseudobirotules, which are umbonate and with only small warts, instead of spines. DNA sequences from the nuclear ITS1-5.8-ITS2 region were sequenced from the holotype and a paratype of the new species to determine their phylogenetic relationships with other members of the family Spongillidae. Tree topologies (Bayesian Inference and Maximum Likelihood) were consistent in showing Racekiela creciscrystae sp. nov. as a sister clade of R. montemflumina confirming its allocation in a monophyletic genus Racekiela. A comparison with all the Racekiela species described so far is also included. This paper increases the number of species of freshwater sponges in Mexico, and confirmed that Racekiela is a monophyletic genus with morphological characters very well defined.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:3769C54F-23C4-409A-AF02-81F3AA084F7A

http://www.zoobank.org/urn:lsid:zoobank.org:act:A512359D-E428-4D04-B08A-E189E3F6F962

KEYWORDS:

• ITS
• molecular data
• freshwater
• Porifera
• Mexico
• new species
• Racekiela

Acknowledgements

The study has been funded by the PAPIIT (Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica, DGAPA), “Diversidad, taxonomía y distribución de esponjas dulceacuícolas del noroeste de México”, IN200716. We also thank Martín López-Hernández for the loan of the Multi-echo System YSI 556 (MPS) kit, Erick Esteban-González and Ricardo Martínez Gómez for the collecting support, Hector M. Alexander-Valdes for the map drawing, and Laura E. Gómez Lizarraga for the SEM photomicrographs.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the PAPIIT (Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica, DGAPA), “Diversidad, taxonomía y distribución de esponjas dulceacuícolas del noroeste de México” [IN200716].