Acostemmini Evans, 1972

Zahniser, James N. & Dietrich, Chris H., 2013, A review of the tribes of Deltocephalinae (Hemiptera: Auchenorrhyncha: Cicadellidae), European Journal of Taxonomy 45, pp. 1-211 : 31-34

Acostemmini Evans, 1972

Fig. 9

Type genus: Acostemma Signoret, 1860 .

= Acroponinae Linnavuori & Quartau, 1975.

Diagnosis

Acostemmini are medium sized to very large yellow, greenish, reddish-brown, brown, or greyish leafhoppers. They can be identified by the single carina on the anterior margin of the head, distinct epistomal suture, forewing with a straight commissural margin (apices not overlapping) and without appendix, pygofer setae reduced or absent, valve fused to pygofer or lateral margin long and articulated with pygofer, style linear-shaped, and subgenital plates sometimes fused to each other.

Description

HEAD. Head subequal to or wider than pronotum. Discal portion of crown glabrous with radial or longitudinal striae. Anterior margin of head with a single transverse carina. Frontoclypeus not tumid; texture mostly shagreen; epistomal suture distinct or evident by change in texture from glabrous, strigate, or irregular above suture to shagreen below. Clypellus widening apically; sometimes long and hourglassshaped. Clypellus apex following or slightly surpassing normal curve of gena. Lorum subequal to or wider than clypellus near base. Antennal bases near middle or posteroventral (lower) corners of eyes. Antennae short, less than 1.5 x width of head. Gena obtusely incised laterally; with fine erect seta beside laterofrontal suture. Antennal ledge weakly developed (carinate or weakly carinate). Ocelli present; close to eyes; on anterior margin of head.

THORAX. Pronotum lateral margin carinate; lateral margin shorter than basal width of eye.

WINGS. Forewing macropterous, submacropterous, or rarely subbrachypterous; appendix absent or reduced; with 3 anteapical cells; veins not raised; veins sometimes with callosities; without reflexed costal veins; A1-A2 crossvein present; apical venation strongly reticulate or not reticulate.

LEGS. Profemur with AM1 seta only or with one or more additional proximal setae; intercalary row with one row of five or more fine setae; row AV with short, stout setae or with relatively long macrosetae. Protibia dorsal surface rounded and convex or flat (AD and PD margins at ~90° angles but not carinate). Metafemur apex macrosetae with 2+2+1. Metatarsomere I not expanded apically; plantar setae simple, tapered.

MALE GENITALIA. Valve straplike, sometimes longer laterally than medially (Acostemella); articulated with or fused to pygofer; if articulated then lateral margin long, with length of articulation long; articulated with or fused to subgenital plates. Pygofer basolateral membranous cleft absent; macrosetae reduced or absent or well differentiated into several rows. Subgenital plates fused or articulated with each other; articulated with or fused to valve; without macrosetae, with macrosetae irregularly arranged, or with macrosetae uniseriate laterally. Style linear, median anterior lobe not pronounced or broadly bilobed basally, median anterior lobe pronounced; apophysis sometimes bent at nearly 90° angle. Basal processes of the aedeagus/connective absent or present, if present then connected to or articulated with connective or base of aedeagus. Aedeagus with single shaft and gonopore. Connective anterior arms widely divergent, T -shaped, or somewhat divergent, Y -shaped; sometimes with an anteromedial lobe or process (Acostemella, Alocoelidia, Caelidioides , Ikelibeloha , Iturnoria ); fused to or articulated with aedeagus.

FEMALE GENITALIA. Pygofer with numerous macrosetae. Ovipositor not protruding far beyond pygofer apex. First valvula convex or not strongly convex; dorsal sculpturing pattern strigate, concatenate, or reticulate; sculpturing reaching dorsal margin; without distinctly delimited ventroapical sculpturing. Second valvula broad, gradually tapered or slender throughout, without dorsal median tooth; teeth restricted to apical 1/4 or less; teeth small, regularly or irregularly shaped.

Geography and ecology

Distribution: Afrotropical and Oriental ( India, Sri Lanka, New Guinea) regions. The diversity of the tribe lays mostly in Madagascar, where it appears to have radiated and subsequently dispersed to mainland Africa, India, and Sri Lanka where species of Acostemma are found. Several undescribed genera and many species have recently been discovered ( Zahniser & Nielson 2012) based on samples from an arthropod biodiversity inventory of Madagascar. Some species in the genus Eryapus resemble bird droppings.

Remarks

Acostemmini contains 12 genera and 27 species. This subfamily is a relictual lineage of Deltocephalinae and retains some primitive features of the male genitalia.

The morphologically enigmatic genus Ikelibeloha and four other genera were included in the tribe by Zahniser & Nielson (2012). They noted that these genera do not share all of the male genitalic characters that previously helped to define the tribe (e.g., valve fused to pygofer) but shared other unique acostemmine characters that supported their placement in the tribe. Ikelibeloha and Iturnoria were included in phylogenetic analyses using only molecular data by Zahniser & Nielson (2012) and formed a monophyletic group with the other sampled acostemmines ( Acostemma and Eryapus ). In the MP analysis here, Ikelibeloha and Iturnoria did not group with the other acostemmines, a result which is likely due to the inclusion of morphological data and the divergent morphology of these taxa as compared to “typical” Acostemmini. However the ML and Bayesian analyses of combined data recovered the two genera as sister to the other included Acostemmini, Acostemma and Eryapus , with strong branch support (85 BS support and 1.0 PP, respectively), thus forming a monophyletic Acostemmini. The previous MP, ML, and Bayesian analyses of only molecular data also strongly supported this relationship ( Zahniser & Nielson 2012). Despite the result of the MP analysis here, the relationships among the earliest lineages of Deltocephalinae as those depicted in the ML and Bayesian trees here (both with moderate to high branch support) showing Stegelytrini as the earliest diverging tribe sister to a monophyletic Acostemmini and the remaining Deltocephalinae are the most well-supported by the available evidence.

Evans (1972 b) tentatively placed Telopetulcus (not examined in this study), recorded only from New Guinea, in Acostemmini. Its placement is still uncertain. Fig. 6A of Evans (1972 b) suggests the presence of the epistomal suture on the face which would indicate that it belongs in Acostemmini, but some other features (e.g., Y -shaped connective articulated with aedeagus) do not occur in other genera of the tribe. Closer examination of this genus is needed with reconsideration of its tribal placement.

Selected references

Evans (1954, 1972 b), Linnavuori & Quartau (1975), Linnavuori & Al-Ne’amy (1983), Zahniser & Nielson (2012).

Included genera

Acostemana Evans, 1954

Acostemma Signoret, 1860

Acostemmella Evans, 1954

Alocoelidia Evans, 1954

Caelidioides Signoret, 1880

Dardania Stål, 1866

Eryapus Evans, 1954

Ikelibeloha Zahniser & Nielson, 2012

Iturnoria Evans, 1954

Malicia Evans, 1954

Protonesis Spinola, 1850

Telopetulcus Evans, 1972

Figures

Fig. 9. Acostemmini. Acostemma stilleri sp. nov. A–I. Standard views (see Material & Methods). F. Plates shown with pygofer. G. Connective and style shown with part of fused aedeagus. H. Aedeagus shown with fused processes, connective, and style. J. Lateral view of style, connective, and base of aedeagus. K. Ventral view of connective, styles, and ventral processes of aedeagus. L. Detail of hairlike extensions of egg. M. Egg. N. ♀ sternite VII.

Fig. 6. ML tree inferred from analysis of molecular data only. This tree is included to illustrate the difference between including or excluding the morphological data from the phylogenetic analyses (see Fig. 5 for comparison of ML-inferred tree with morphological data). This analysis is the only one performed here to include Dorycephalus (Dorycephalini), and its position is highlighted.