19. Tribe OXYRHACHINI Distant 1908 Old World: Afrotropical, Indomalayan, and Palearctic Regions Figs. 19.1-19.3 Type genus: Oxyrhachis Germar, 1833a Oxyrhachisaria Distant, 1908g [new division]: first treated as subfamily Oxyrrhachinae [sic: for Oxyrhachinae] and tribe Oxyrrhachini (Haupt 1929c); tribe Oxyrhachisini [sic: for Oxyrhachini] Goding 1930b; subfamily Oxyrhachinae equals Centrotinae and tribe Oxyrhachini moved to Centrotinae (Dietrich et al. 2001a). Xiphistesini Goding, 1930a [new division]: first treated as tribe Xiphistini and equals Oxyrhachini (Capener 1962a). Diagnostic characters.—Frontoclypeal lobes indistinct, head with large foliate lobes. Posterior pronotal process concealing scutellum. Pleuron with propleural lobe present and mesopleural lobe enlarged. Forewing with Cu1 vein abutting clavus (not marginal vein), with m-cu1 and m-cu2 crossveins in at least one wing, M and Cu veins adjacent at base, base of R2+3 and R4+5 veins truncate. Hind wing with R4+5 and M1+2 veins fused or not (3 or 4 apical cells). Tibiae foliaceous. Mesothoracic and metathoracic femora without ab- and adlateral cucullate setae. Metathoracic tibial rows I and III without cucullate setae (row II without cucullate setae in some species). Female second valvulae short with undulating dorsal margin, narrow near base, not curved, dorsal margin with fine teeth. Male style clasp oriented laterally, apex membranous, cylindrical, angled ventrally. Abdomen with paired 283 dorsal swellings, larger in posterior segments; acanthae distinct, bases not heightened, acanthae without ornamentation. Description.—Length 5-6.3 mm. Color tan to dark brown, or combinations thereof. HEAD (Fig. 19.1 I): frontoclypeal margins parallel or slightly converging ventrally, frontoclypeal lobes indistinct; with large foliate lobes; ocelli about equidistant from each other and eyes; vertex without toothlike projections. THORAX: PRONOTUM (Figs. 19.1 A- H): suprahumeral horns present or absent; posterior process straight at base, appressed against scutellum, significantly extending past m-cu3 crossvein in forewing. SCUTELLUM: emarginate with apices acute, concealed by posterior process; shortened--with abdomen removed, notch and apices not visible. PLEURON: propleural lobe present, mesopleural lobe enlarged. FOREWING (Figs. 19.1 J): hyaline; apical limbus broad; s crossvein distad of r-m2 crossvein; Cu1 vein abutting clavus (not marginal vein); m-cu1 and m-cu2 crossveins present in at least 1 wing; M and Cu veins adjacent at base; R and M veins not confluent preapically; R1 vein not perpendicular to marginal vein; r-m1 crossvein originating anterior to first division of R vein, parallel to longitudinal veins or bent towards R vein; R, M, and Cu veins not parallel apically; R4+5 vein shape prior to s crossvein significantly angled or not; base of R2+3 and R4+5 veins truncate. HIND WING (Fig. 19.1 K): R4+5 and M1+2 veins fused or not (3 or 4 apical cells). PRO- AND MESOTHORACIC LEGS: tibiae foliaceous; mesothoracic tibia without row(s) of cucullate setae; mesothoracic femur without ab- and adlateral cucullate setae. METATHORACIC LEG (Figs. 19.2 A-B): ventral margin of coxa, trochanter, and femur without enlarged setal bases; femur without ab- and adlateral cucullate setae; femur without ablateral cucullate setae ventrolaterally; tibia foliaceous, rows I and III without cucullate setae; row II with or without cucullate setae, if present, in single row; tarsomere I with 1 cucullate seta or 284 none. ABDOMEN: in anterior aspect (abdomen removed) nearly triangular; anterior tergal borders not modified; sternal longitudinal carina absent; paired dorsal swellings present, larger in posterior segments; tergum III ventrolateral margin carinate; abdominal setal bases not enlarged. FEMALE GENITALIA (Figs. 19.3 A-D): second valvulae short with undulating dorsal margin, narrow near base, not curved, dorsal teeth fine in size, acute projections on dorsal margin absent; third valvulae without small ventral conelike projections. MALE GENITALIA (Figs: 19.3 E-K) lateral plate with short dorsoapical lobe extending laterally (Fig. 19.3 J) or vertically, without ventral lobe; subgenital plate without distinct division; style clasp (Fig. 19.3 E-F) oriented laterally, membranous, cylindrical, angled ventrally; style shank arched, apex at midpoint or past midpoint. ABDOMINAL FINE STRUCTURE (Figs. 19.2 C-D): acanthae distinct, bases not heightened, acanthae without ornamentation. Chromosome numbers.—Male 2n= 21 (Table 26.3). Distribution.—The tribe Oxyrhachini is recorded from the Afrotropical, Indomalayan, and Palearctic Regions (McKamey 1998a). Ecology.—Members of the tribe Oxyrhachini are reported from the host plant families Amaranthaceae, Balanitaceae, Bignoniaceae, Buddlejaceae, Casuarinaceae, Compositae, Ebenaceae, Euphorbiaceae, Gramineae, Lauraceae, Leguminosae, Moraceae, Myrtaceae, Proteaceae, Rhamnaceae, Santalaceae, Solanaceae, Sterculiaceae, Tamaricaceae, Ulmaceae, and Verbenaceae. Oxyrhachis is the only centrotine genus reported from the family Balanitaceae (Table 26.2). Oxyrhachis is reported to be tended by ants (Table 26.1). Some species of Oxyrhachis are gregarious intra- and interspecifically as both nymphs and adults (Ananthasubramanian 1996a). In addition, certain species of Oxyrhachis show 285 parental care by guarding egg masses and nymphs from predators and parasitoids (Ananthasubramanian 1996a). Discussion.—The tribe Oxyrhachini, represented by the genus Oxyrhachis, is a very morphologically distinct, geographically widespread, and speciose group. The genus Oxyrhachis is among the four largest membracid genera, with 117 species (McKamey 1998a). Oxyrhachini, although monotypic, is here retained as a valid tribe due to the numerous character changes on the phylogenetic tree (Fig. 24.1) and the size of the lineage. The genus Oxyrhachis is perhaps best known morphologically for its large foliate lobes on the head that closely border the frontoclypeus. Oxyrhachini was historically placed in the Membracinae by many workers including Stål (1866a), Distant (1908g), Goding (1931a), and Metcalf and Wade (1965a). Funkhouser (1951a), however, included the Oxyrhachini within the Centrotinae. Distant’s (1908g) key characteristics are still valuable diagnostic features for the tribe: oxyrachine treehoppers have a long and narrow posterior process, the tibiae are foliaceous, and the pro- and mesosterna have distinct tooth-like processes. Along with these features, all oxyrhachines examined have dorsal abdominal swellings which are larger in the posterior portion of the abdomen. This is in contrast to nessorhinines and gargarines where the dorsal abdominal processes are more distinct in the anterior portion of the abdomen. Unlike other centrotines, the oxyrhachines examined here have Cu1 vein abutting the clavus in the forewing, or the junction between the clavus and the marginal vein, rather than clearly abutting the marginal vein. Additionally, M and Cu veins in the forewing are clearly adjacent in oxyrhachine forewings and m-cu1 and m-cu2 crossveins are present. 286 Although most oxyrhachine species are morphologically homogenous, certain characters vary among species. Some species, including O. carinata and O. sulicornis, have R4+5 and M1+2 veins in the hind wing fused (3 apical cells) while in other species these veins are not fused (4 apical cells). Apparently, according to Capener (1962a), the number of species with 3 apical cells and 4 apical cells in the hind wing is about equal. The presence of cucullate setae in metathoracic tibial row II is also variable among species of Oxyrhachis. Indeed, Oxyrhachis formerly was split into 6 genera to accommodate the differences in hind wing venation and pronotal features, including the presence or absence of suprahumeral horns. Based on a phylogenetic analysis (Fig. 24.12) of three former genera (Gongroneura Jacobi, Kombazana Distant, and Xiphistes Stål) and Oxyrhachis, however, there are too few morphological differences to defend splitting Oxyrhachis into multiple genera at this time. A phylogenetic analysis of Oxyrhachis, using generic morphological characters and molecular methods, is recommended to better determine its taxonomic and phylogenetic limits. The reduction in rank from subfamily Oxyrhachinae to tribe Oxyrhachini (within the Centrotinae) by Dietrich et al. (2001a) based on a morphological phylogenetic analysis is supported by the phylogenetic analysis of the Centrotinae presented here (Fig. 24.1). The Oxyrhachini are closely related to the tribes Ebhuloidesini, Hypsaucheniini, and Terentiini. Apparently, the Oxyrhachini are sister group to the Hypsaucheniini. The Ebhuloidesini, Hypsaucheniini, and Oxyrhachini share similarly shaped female second valvulae and male clasps, and all have enlarged pleural projections. This diagnostic male clasp was described as resembling the “head of a snake” by Capener (1962a). Although the Oxyrhachini are sister group to the Nessorhinini in the phylogenetic analysis of Dietrich et al. (2001a), this relationship was thought to be an artifact of the small number of centrotines sampled. It is 287 critical that future molecular higher level phylogenetic analyses of the Membracidae include the Oxyrhachini in order to investigate further their relationship with the morphologically extreme tribe Hypsaucheniini and predominantly Australian Terentiini. Genera of the tribe Oxyrhachini Oxyrhachis Germar, 1833a (type species: Membracis taranda Fabricius by monotypy). Specimens examined. —Oxyrhachis