Braxtonota, Dietrich, 2008

Dietrich, C. H., 2008, Some remarkable new Neotropical treehoppers (Hemiptera: Cicadomorpha: Membracidae), Zootaxa 1727, pp. 29-38 : 35-37

Braxtonota new genus

( Figs 5, 8, 11, 15, 16)

Type species: B. enigmata n. sp.

Diagnosis. This genus resembles other Caribbean Centrotinae in having the pronotum contacting the scutellum dorsally throughout its length, the mesothoracic femur without cucullate setae, and the abdominal terga with anterior borders modified into irregular ridges, but may be readily distinguished by the following combination of features: frontoclypeus in profile not projecting ventrad; pronotum without suprahumeral horns, not concealing scutellum laterally, with pair of lateral carinae extended posterolaterad from midline; hind femur without supranumerary cucullate setae; second valvulae broad at midlength, tapered towards apex, without large teeth.

Description. Medium sized (7 mm). Coloration. Mottled brown. Structure. Head ( Fig. 11) with vertex slightly less than twice as wide as long, with distinct dorsomedial concavity, elevated medially but without paired dorsal projections, median carina weak; ventral lobes broadly rounded, weakly produced, and slightly upturned. Ocellus slightly closer to corresponding eye than to midline, approximately even with dorsal margins of eyes. Frontoclypeus flat, depressed dorsomedially, not projecting ventrad in profile; lateral lobes well developed, extended to midlength. Rostrum extended well beyond posterior coxae. Pronotum extended over and covering scutellum dorsally but only partially concealing scutellum laterally; suprahumeral horns absent; pair of lateral carinae extended from midline just anterad of humeral angles posterolaterad to lateral margin just dorsad of exposed part of scutellum; median crest present posterad of humeral angles; posterior process extended beyond apex of abdomen; dorsal postocular carina obsolete anteriorly; ventral postocular carina absent. Scutellum emarginate, exposed posterolateral lobes pilose. Forewing ( Fig. 15) with opaque punctate sclerotization restricted to small areas adjacent to base of costal margin and base of clavus; R 1 relatively long, continuous with R stem; Rs contacting M at single point or crossvein r-m 1 very short; crossvein r-m 2 equidistant from s and Rs fork; M 3+4 abruptly bent toward anal margin distally near apex; pterostigma absent. Hind wing with R 1+2 and M 3+4 free, connected by crossvein. Pro- and mesothoracic legs lacking cucullate setae, tibiae slender. Metathoracic femur with ablateral cucullate seta present near apex; adlateral cucullate seta distinctly preapical; tibia with three well developed single rows of cucullate setae. Abdominal terga without distinct paired dorsomedial swellings; tergum III with upcurved anterolateral groove; sternites without carinae. Female with second valvulae ( Fig. 8) gradually broadened from base to midlength, thence evenly tapered to apex; dorsal margin finely serrate, without prominent teeth. Male unknown.

Notes. Given the features mentioned above in the diagnosis, Braxtonota will key to couplet 9 in the tribal key of Wallace and Deitz (2004), comprising the two tribes of Centrotinae endemic to the Caribbean region: Monobelini and Nessorhinini . Because it lacks “extra” cucullate setae at the apex of the metathoracic femur (a key feature for Monobelini), Braxtonota will key to Nessorhinini . The structure of the head of Braxtonota is similar to that of Nessorhinus in that the frontoclypeus is flat, without a ventral projection, and the midline of the vertex is carinate; these features are lacking in Monobelini. The posterior pronotal crest of Braxtonota is also somewhat similar to that of N. vulpes Amyot & Serville. Nevertheless , the new genus lacks two key features of Nessorhinini : paired dorsal abdominal swellings and slender second valvulae with prominent teeth. It also lacks the median longitudinal carina that is present on the frontoclypeus of many members of Nessorhinini and has the scutellum exposed laterally, which is rare in that tribe. The broad, finely serrate second valvula of Braxtonota resembles that of Monobelus ( Wallace and Deitz (2004): Fig. 17.4D), but this apparently plesiomorphic form is found in many other centrotine and non-centrotine membracids, and the other two genera of Monobelini have the second valvulae narrow with prominent teeth, as in Nessorhinini . Based on the combination of features present in the new genus, including its lack of suprahumeral horns, the genus seems most appropriately placed in Monobelini, although this placement should be considered tentative.

Discovery of Braxtonota , which shares unique features with both Monobelini and Nessorhinini , but lacks the definitive synapomorphies that would place it unequivocally in either of those tribes, suggests that these endemic Caribbean groups are more closely related than implied by the phylogenetic results of Wallace and Deitz (2004). Indeed, although the phylogeny presented by Wallace and Deitz placed Monobelini as sister to a clade comprising Boocerini and Gargarini and Nessorhinini as sister to Platycentrini, Monobelini and Nessorhinini are similar in many respects. As noted above, they key to the same couplet in Wallace and Deitz (2004) based on their pronotal structure and leg chaetotaxy. Although the relationship suggested by these possibly synapomorphic key features was outweighed by other characters included in the analyses of Wallace and Deitz (2004), some of the putative synapomorphies that united Monobelini with Boocerini and Gargarini in their analysis—e.g., a longitudinal carina on abdominal sternum III, forewing crossvein r-m 1 arising near or distad of initial division of R—also occur in some Nessorhinini . Likewise, some synapomorphies that supported Nessorhinini in their analysis—e.g., presence of large teeth on second valvulae, style clasp truncate with acuminate projection—are present in some Monobelini.

The genus is named in honor of my wife, Susan M. Braxton, combining her surname with – nota, a suffix commonly employed in forming membracid generic names. The gender is feminine. This genus is based on a single female specimen of a new species, described below.