A dichotomous key and checklist for Mexican Athysanini leafhopper genera (Hemiptera: Cicadellidae) with a new species from the Oaxacan dry tropical forest

Most Neotropical forest-dwelling leafhopper species are rare and exhibit limited distributions. The Mexican leafhopper fauna is known to be highly diverse and identifi cation of genera and species is diffi cult because no attempts have been made to provide comprehensive identifi cation tools for the fauna. Here, a dichotomous key to all genera recognized within Mexico of the diverse but little studied leafhopper tribe Athysanini is provided. Spinulana josefi nae Pinedo-Escatel sp. n. is described and illustrated based on specimens collected in the dry tropical forest of Oaxacan mountains. A total of 46 genera and 146 species are now recognized in the checklist of Athysanini of Mexico. Notes on type repositories, distributional data and maps, and selected references are provided. ZooBank Article Registration: http://zoobank.org/urn:lsid:zoobank.org:pub:FE90D7C2-C3FE-47B8-928F-68A0405C4141

into other, better-defi ned deltocephaline tribes (Zahniser & Dietrich, 2013). The tribe includes many members that are highly specialized on host plants or habitats with distributional ranges limited and rarely extended beyond particular habitats or regions.
From the 1920s to the 1940s a comprehensive series of surveys on Mexican leafhoppers conducted by Dr. D.M. DeLong of Ohio State University (USA) and colleagues suggested that a large percentage of athysanine leafhopper species inhabit only specifi c areas within particular types of forests in western or central Mexico. Additional distributional records have not been published for most of the species documented in these original surveys. Thus, additional surveys are needed to further elucidate the distributions and conservation status of these endemic Mexican taxa.
Mexico is recognized as a megadiverse country with highly endemic genera and a mixture of Nearctic and Neotropical cicadellid faunas. The leafhopper fauna of Mexi- One of the largest herbivorous insect families worldwide is Cicadellidae (Hemiptera: Auchenorrhyncha: Cicadomorpha: Cicadoidea), which currently comprises more than 22,800 and in Deltocephalinae up to 7,100 species (Dietrich, 2005;Zahniser & Dietrich, 2013). The Americas harbor a diverse leafhopper fauna comprising 22 subfamilies (Dietrich, 2005). Within this family, the subfamily Deltocephalinae is the largest, with over 6800 species distributed in all major geographical regions. This morphologically diverse subfamily comprises 39 tribes, of which the forest-dwelling tribe Athysanini is the largest and most widespread with nearly 230 genera and 1,150 species known (Zahniser & Dietrich, 2013).
Athysanini comprises 126 genera occurring in the New World with high diversity and richness in both northern and southern regions of the Americas (Linnavuori, 1959;Oman et al., 1990). This tribe, as presently defi ned, is polyphyletic, comprising all the genera that could not be placed Morphology. Length 2.5-7 mm. Body color green, brown, ochraceous, pale, reddish, orange or black, or combination, often including symmetrical stripes, spots or bands, or irregular patterns. Head subequal, wider or narrower than pronotum. Crown usually shagreen anteriorly with posterior part longitudinally striate or glabrous, anterior margin without distinct transverse carinae. Frontoclypeus weakly convex with texture shagreen. Anteclypeus parallel-sided or widening apically with apex following or slightly surpassing normal curve of gena. Lorum often wider than anteclypeus near base. Antennal ledge absent, antennal base near midheight of eyes. Pronotum with transverse striations very weak or absent, lateral margin usually much shorter than half eye width. Forewing macropterous with appendix narrow and restricted to anal margin; with 3 anteapical cells; with or without veinlets or false veins along costal margin. Hind wing venation fully developed, without pigmentation, RP-MA and MP-CuA separated by crossvein. Front femur AM row with only apical seta present; row AV usually with several short stout setae in basal half. Front tibia usually with dorsal macrosetal formula 1 + 4 (AD + PD). Mesotrochanter with one stout seta. Hind femur macrosetal formula 2 + 2 + 1, without extra setae basad of usual set. Metatarsomere I not expanded apically, plantar setae simple, pecten usually with 3-4 platellae.
Genitalia. Male pygofer lobe with numerous macrosetae scattered over distal half; dorsal or ventral processes or teeth sometimes present; basolateral cleft present. Anal co has not been investigated thoroughly although a large number of short taxonomic contributions were published by DeLong based on specimens collected in the early to mid-1900s. Many regions remain understudied and knowledge of the fauna is far from complete. Also, identifi cation of Mexican leafhoppers is diffi cult because there have been no attempts to provide comprehensive identifi cation tools. Here we provide the fi rst key to all genera of the tribe Athysanini known to occur in Mexico. A new species in the genus Spinulana DeLong, 1967 living on trees of the dry tropical forest from Oaxacan mountains is also described and the fi rst annotated species checklist of this tribe for the country is included.

Annotated list preparation
Each checklist entry provides information in order as follows: taxon name, author and year of description, synonyms and original combination, citation, type material repository, distribution including Mexican political division, host plants, and additional relevant references at generic level. The genera and species are arranged alphabetically.

Distributional data
A series of layout maps were built following the criteria of Morrone et al. (2017) for Mexican biogeographic regionalization. Mapped points were generated and referenced using information from the literature, specimens collected by the fi rst author and colleagues, and major museum specimen holdings (Table S1). tube membranous or partially sclerotized but not elongate. Valve and subgenital plates free from each other, articulated with pygofer. Subgenital plate macrosetae uniseriate or somewhat irregularly arranged near lateral margin. Connective Y or H-shaped with anterior arms well separated and parallel to moderately divergent, stem movably articulated to aedeagus, without posterior extension or paraphysis. Style broadly bilobed basally; median anterior lobe not elongated. Aedeagus with or without processes. Phragma weakly sclerotized or membranous, dorsal connective absent.
Remarks. Most traits mentioned in the above tribal description may be found in one or more other tribes of Deltocephalinae. Previous phylogenetic analyses (e.g., Zahniser & Dietrich, 2013) indicate that Athysanini is polyphyletic. The included genera have traditionally been retained here because they lack the distinctive, presumably derived, morphological traits diagnostic for other recognized deltocephaline tribes. Nevertheless, most Athysanini can be distinguished from other Deltocephalinae by a combination of the structure of the head (crown anterior margin without transverse carinae and anteclypeus parallel-sided or broadened distally) and male genitalia (anal tube short and incompletely sclerotized, connective Y-shaped and articulated to aedeagus, without posterior extension or paraphysis, dorsal connective absent).

Diagnosis
Spinulana josefi nae sp. n. can be distinguished by the combination of the following characters: head slightly produced, dorsal coloration light-brown with yellowish marks, crown with a large black spot beside each eye and four minute black spots adjacent to midline near anterior margin, and pygofer with bifi d asymmetrical caudal process.

Description
External morphology. Overall color light-brown with dorsal, ventral and anterior yellowish marks ( Fig. 2A-E). Crown yellowish with a light-brown broad line on anterior margin; two pairs of symmetrical black spots, outer pair next to eyes and larger than inner pair on midline; ecdysial line with arcuate light-brown band with two minute black spots centrally; midlength shorter than eye to midline ( Fig. 2A-B). Ocellocular area tapering to ocelli; a black spot above antennal pit. Ocelli surrounded by triangular black spots. Frontoclypeus mostly yellowish with some transverse black lines arising mesad of lateral suture, upper area with pair of triangular black marks, lower area marked with black; midline yellowish. Antleclypeus with inverted black T-shaped macula mediall, yellowish laterally. Lorum mostly yellowish with margins black. Genae yellowish with a black marks below antenna (Fig. 2C). Pronotum with brownish and ivory transversal bands, a paired slender black stripes posteriorly. Forewing translucent. Veins dark-brown (Fig. 2D). Venter yellowish with some blackmarks. Legs with black and brown patches (Fig. 2 E).
Male genitalia. Pygofer lobe in lateral view longer than tall, squarish, macrosetae long and reduced with two or one row of four setae near posterior margin (Fig. 3A); pygofer process on ventral margin asymmetrically bifurcated in ventral view (Fig. 3B). Segment X one third as long as py-gofer; dorsal and lateral sides fully sclerotized; base to apex uniform and rectangular. Valve weakly projected posterad with rounded apical margin; 2.2 × wider than long. Plate extended to pygofer apex; macrosetae uniseriate laterad, concentrated near midlength with fi ne setae intercalated; apex truncate ( Fig. 3C). Style broad basally with preapical lobe weakly developed, apophysis very short, straight, not expanded, apex rounded and blunt (Fig. 3E). Connective stem apex slightly emarginated, shorter than arms (Fig.  3D). Aedeagus curved dorsad; without basal processes; shaft slender with lateral fl anges; apex rounded with minute notch; gonopore apical and wide as shaft ( Fig. 3F  Habitat. Oaxacan dry tropical forest. Remarks. This species differs from S. varigata DeLong and S. spinosa DeLong in having one short and asymmetrically bifi d caudal pygofer process ( Fig. 2A and B). The new species belongs to a distinct endemic group recently expanded based on study of DeLong's type material and other specimens (Pinedo-Escatel & Dietrich, 2020a).          Kramer & DeLong (1969), Lindsay (1939 Norvellina acuspina Kramer & DeLong, 1969 Norvellina acuspina Kramer & DeLong, 1969: 115 OSUC (holotype and paratypes) Endemic to Mexico (CHIS)

DISCUSSION
The tribe Athysanini is widely distributed in Mexico but individual species vary signifi cantly in distribution and nearly two thirds of their diversity is concentrated in the Mexican Transition Zone of central Mexico, which is home to a diverse fl ora and fauna of Nearctic and Neotropical species (Figs 4 and 5, also see Fig. 6 in Pinedo-Escatel et al., 2021). Plant associations remain poorly known for most species and available data are mainly for groups residing within particular habitats, e.g., Tropical Dry Forest and Pine/Oak Forest (Aguilar-Pérez et al., 2019;Pinedo-Escatel et al., 2021). Despite extensive recent collecting, many species are still known only from the original type series collected in the 1930s and 40s and may be endangered or extinct . Mexico harbors nearly 30% of the endemic genera of Athysanini recorded from the New World and harbors the largest number of endemic athysanine genera of any New World country (Oman et al., 1990;Pinedo-Escatel et al., 2021). Thus, additional collecting efforts, particularly in relatively intact tropical forests, will likely continue to yield new species of this group.
Identifi cation of Neotropical genera of Athysanini, particularly those endemic to Mexico, is often diffi cult. DeLong's original descriptions and illustrations omit many important details and Linnavuori (1959) did not include most of the endemic Mexican genera described by DeLong in his key to Neotropical Deltocephalinae. Cwikla & Blocker (1981) provided brief diagnoses and comparative notes for some of the endemic Mexican genera not included by Linnavuori (1959) but did not provide a revised key or additional illustrations. Thus, until now, identifi cation of these genera has required review of original descriptions and illustrations in DeLong's numerous short taxonomic publications or reference to authoritatively identifi ed specimens from DeLong's collection at Ohio State University.
The key to genera provided above represents a fi rst step toward a more comprehensive revision of New World Athysanini. As noted previously, Athysanini is a poorly defi ned, polyphyletic group and its classifi cation needs to be revised comprehensively based on phylogenetic analysis. The most comprehensive previous phylogenetic analysis of Deltocephalinae included only 16 endemic New World athysanine genera but recovered two almost exclusively New World clades comprising these endemic Athysanini and the endemic New World tribes Bahitini, Pendarini, and Scaphytopiini (Zahniser & Dietrich, 2013). This suggests that the New World members of Athysanini evolved independently from Athysanini genera that are endemic to other continents or widespread in the Holarctic. More detailed phylogenetic analyses of these New World lineages are needed not only to elucidate the phylogenetic status of individual endemic tribes and genera but also to reveal patterns of biogeography, host and habitat use that could explain their evolutionary diversifi cation.