Nomenclatural changes in the grass-feeding Mexican leafhopper genus Cocrassana Blocker & Larsen (Hemiptera: Cicadellidae: Deltocephalinae: Athysanini)

ABSTRACT

Two nomenclatural changes are proposed in the tribe Athysanini (Cicadellidae: Deltocephalinae). Chlorotettix sexvarus DeLong, 1959, is newly placed in the genus Cocrassana Blocker & Larsen and is a senior synonym of the type species of Cocrassana, C. riepmai Blocker & Larsen, 1991, syn. nov. A revised diagnosis and illustration of the species are provided.

Keywords:
Taxonomy; Combination; Synonymy; Auchenorrhyncha; Cicadomorpha; New status

Introduction

Deltocephalinae is the largest and most morphologically diverse group of leafhoppers worldwide. Every year many species are described as new, reclassified, or synonymized. In subtropical regions of Mexico, there is a high incidence of unusual leafhoppers in Deltocephalinae. D. M. Delong's original surveys of the Mexican leafhoppers led to the recognition of many monotypic genera and many of these remain little studied.

The genus Chlorotettix Van Duzee, 1892, is well represented in Mexico and comprises 25 species within the country. DeLong (1959) described C. sexvarus remarking on its three distinct pairs of black spots on the crown, pronotum, and scutellum. He illustrated the male genital capsule and showed the peculiar arrangement of pygofer spines and processes on the aedeagus. No additional information has been published on this species. Subsequently, while sorting leafhopper samples collected in Mexico from cultivated crops and their wild relatives (e.g., Zea perennis and Z. mays) Blocker & Larsen (1991) erected the deltocephaline genus Cocrassana with a single species, C. riepmai, noting that the genus may be easily separated from other deltocephalines by the combination of male genital features.

Examining the type of material of C. riepmai and C. sexvarus revealed that they are very similar and should be regarded as representatives of the same species. Thus, in compliance with International Code of Zoological Nomenclature (ICZN, 1999) according to Article 57.2 and 60, we propose a new synonymy and combination for taxonomic clarity.

Material and methods

The dry, pinned holotype specimens of both species, C. riepmai (Fig. 1) and C. sexvarus (Fig. 2), in addition to recently collected and preserved material in alcohol from Mexico were examined. Abdomens of specimens were removed and cleared in hot 10% KOH, rinsed in water and then stored in glycerine. Dissections of genital structures were performed in distilled water. Internal morphology was observed under a stereoscopic microscope (Carl Zeiss) and drawn using a camera lucida attached to the microscope. Images of habitus were taken using a Nikon camera. Multiple images were stacked to obtain precise pictures and edited in Photoshop to show fine details. Abbreviations cited in the text are as follows: The Ohio State University, Triplehorn Insect Collection (OSUC), Columbus, USA; Colección de Auchenorrhyncha de Jorge Adilson Pinedo Escatel (CAJAPE), Mexico; and U.S. National Museum of Natural History, Smithsonian Institution, Washington, D.C. (USNM).

Figure 1
Cocrassana sexvarus (DeLong) comb. nov., male holotype. (A) Lateral habitus. (B) Dorsal habitus. (C) Labels and microvial containing genitalia of specimen.

Figure 2
Cocrassana sexvarus (DeLong) comb. nov., male holotype of junior synonym C. riepmai Blocker & Larsen. (A) Lateral habitus. (B) Dorsal habitus. (C) Labels and microvial of genitalia of specimen.

Results

Cocrassana sexvarus (DeLong, 1959) comb. nov.

Chlorotettix sexvarusDeLong, 1959: 326 [n. sp.]

Cocrassana riepmaiBlocker & Larsen, 1991: 124, syn. nov.

Remarks. As noted by Cwikla in his unpublished PhD dissertation (1988), this species was incorrectly placed in Chlorotettix by DeLong (1959). Cwikla (1988) proposed transferring the species to the genus Crassana DeLong & Hershberger but this action was never validated by publication as required by the ICZN. Species of Chlorotettix (currently placed in the tribe Pendarini) have the crown texture uniformly granulose, whereas Cocrassana and other “Crassana-like genera” sensu Blocker & Larsen (1991) have the posterior portion of the crown either smooth, shiny or with fine oblique striations. Cocrassana differs from other genera in the group in having paired fuscous spots rather than a transverse band on the crown and the aedeagus with paired processes at the base of the shaft.

Examination of the holotypes of the two taxa treated here as synonyms revealed that they are slightly different in body color including the relative sizes of the paired brown spots on the crown, pronotum, mesonotum and forewings, and the intensity of the dark longitudinal dorsal band on the abdomen. In the male genital capsule, the two specimens differ slightly in the size, length and thickness of the pygofer appendages, the length of style and the curvature of its apophysis (Fig. 3). These differences are not considered sufficient to justify recognizing the two taxa as distinct species.

Figure 3
Cocrassana sexvarus (DeLong) comb. nov., abdomens and male genitalia of (A-C) holotype of Chlorotettix sexvarus DeLong and (D-F) holotype of Cocrassana riepmai Blocker & Larsen. (A and D) Dorsal aspect of abdomen. (B and E) Pygofer and processes, ventral aspect. (C and F) Style, ventral aspect.

Geographical distribution. Endemic to Mexico, reported from the following states: Jalisco (Amacueca; Zapopan; Autlán; El Grullo; El Arenal), Michoacán (Tuxpan), Morelos (Cuautla; Cuernavaca; Tepalcingo), Campeche (Escárcega), San Luis Potosí (Huichihuayan), and Veracruz (Fortín).

Phenology and biological notes.Pinedo-Escatel & Moya-Raygoza (2015, 2018), reported specimens collected during February (four individuals) and December (four ind.) in 2013, and January (four ind.), February (one ind.), March (four ind.), April (eight ind.), May (two ind.) and October (one ind.) during 2014, May (one ind.) and December (one ind.) in 2017, and June (five ind.) in 2017. It is not reported as a vector of plant pathogens and no natural enemies have been found.

Host plant. Wild grasses, Tripsacum pilosum, T. dactyloides, Zea perennis, Brachiaria plantaginea, Digitaria ciliaris, Cynodon plectostachyus, C. dactylon, Rhynchelytrum repens, Eleusine indica (Poaceae), and the cultivated crops, Z. mays, Citrus × limon (Rutaceae), and Ficus carica (Moraceae).

Type of material examined. Cocrassana riepmai-Holotype ♂ (OSUC), Instituto de Botanica, Univ. Guadalajara, Zapopan, Jalisco, MEX 10-X-89\Collectors: K. J. Larsen & F. E. Vega\Collected from: Zea perennis; Paratypes, 4♂, 5♀ (OSUC) same data as holotype; Paratype ♂ (OSUC)-Int. de Botanica, Univ. Guadalajara, Zapopan, Jalisco, MEX 27-III-90\Collected from: Tripsacum pilosum\Collectors: K. J. Larsen and W. E. Styer. Chlorotettix sexvarus-Holotype ♂ (OSUC) X-8 Mexico\D-122\D. M. DeLong collection.

Other material examined. 1♂ (USNM) – MEXICO: Mor./Cuautla/IV-1965/N.L.H. Krauss; 3♂, 1♀ (CAJAPE) – MEXICO: Jalisco, Zapopan, Las Agujas, 20º44'38.14"N–103º30'44.45"O, a 1663 m, 10-Feb-2013, ex: pastos. Col. J.A. Pinedo-Escatel. 2♂, 9♀ (CAJAPE) – MEXICO: Jalisco, Zapopan, Las Agujas, 20º44'38.14"N–03º30'44.45"O, a 1663 m, 08–Enero–2013, ex: pastos. Col. J.A. Pinedo-Escatel. 1♂, 1♀ (CAJAPE)—MEXICO: Jalisco, Zapopan, Las Agujas, 20º44'38.14"N–103º30'44.45"O, a 1663 m, 01–Marzo–2013, ex: pastos. Col. J.A. Pinedo-Escatel.

Acknowledgments

We thank Luciana Musetti (OSUC) for loaning the material and for permission to take photographs. C. H. Dietrich was supported in part by US National Science Foundation Grant DEB-1639601. To Edith Blanco-Rodriguez for additional data of records, phenology and hosts provided. Access to Photoshop software was supported by the University of Guadalajara. The first author is grateful to Consejo Nacional de Ciencia y Tecnología (CONACyT) for Ph.D. scholarship (CVU: 705854) and the invaluable help of Doctorado en Ciencias en Biosistemática, Ecología y Manejo de Recursos Naturales y Agrícolas (CUCBA), Universidad de Guadalajara. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA. USDA is an equal opportunity employer.

References

• Blocker, H.D., Larsen, K.J., 1991. A new leafhopper genus Cocrassana (Homoptera: Cicadellidae), from Mexican Tripsacinae and a synopsis of related genera. J. Kans. Entomol. Soc. 64, 123-126.
• Cwikla, P.S., 1988. A systematic study of the leafhopper genus Chlorotettix (Homoptera: Cicadellidae). PhD dissertation, Ohio State University. Columbus, 467.
• DeLong, D.M., 1959. A new genus Renonus, and two new species of Mexican leafhoppers (Homoptera: Cicadellidae). Ohio J. Sci. 59, 325-326.
• ICZN, 1999. International Code of Zoological Nomenclature, fourth Edition. The International Trust for Zoological Nomenclature, London.
• Pinedo-Escatel, J.A., Moya-Raygoza, G., 2015. Diversity of leafhoppers during the winter dry season on perennial grasses bordering harvested fields of maize Southwest. Entomology 40, 263-272.
• Pinedo-Escatel, J.A., Moya-Raygoza, G., 2018. Diversity of Leafhoppers (Hemiptera: Cicadellidae) associated with border grasses and maize during the wet and dry seasons in Mexico Environ. Entomology 47, 282-291.

Publication Dates

• Publication in this collection
  Jul-Sep 2018

History

• Received
  2 May 2018
• Accepted
  29 June 2018