Sobarocephala geniculata Sasakawa
Creators: name: Lonsdale, Owen
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Clusiidae
Sobarocephala
Sobarocephala geniculata

description: Sobarocephala geniculata Sasakawa
Fig. 2
Sobarocephala geniculata Sasakawa, 2011: 11.
Redescription (Fig. 2). Male. Body length 3.0– 3.6mm. Setae brown. Types in poor condition with aristae, first flagellomeres and most setae missing. Notal setae partially evident from sockets: two dorsocentral setae, one pair of lateral scutellar setae; acrostichal and presutural intra-alar setae absent. Head light yellow, whitish below frons, with ocellar tubercle brown, and back of head mostly brown above foramen excluding dorsomedial region; face particularly soft (collapsed); posterior margin of frons (vertex) strongly incurved with ocelli and posteromedial corner of eye shifted forwards, and frons much narrower than eye seen dorsally; gena shallow anteriorly and deep posteriorly, forming large silvery-tomentose triangle with occiput (similar to state seen in many Allometopon). Notum yellow with curved brown stripe along anterior margin of scutum, katatergite brown, and scutellum light yellow; postsutural stripes reported in Sasakawa (2011) appear to be absent, with darker region attributable to underlying muscle attachment. Pleuron light yellow (contrasting slightly darker scutum which may only differ due to state of preservation). Legs yellow. Halter entirely pale. Wing with faint anterodistal infuscation. M1+2 ratio approximately 2.3. Abdomen of paratype dark brown; abdomen of holotype (from Sasakawa (2011)) with “T1, T2 and anterior half of T3 yellowish brown, posterior half of T3, T4–6, and S8 black; epandrium shining black, surstylus pale brown”.
Female. Unknown.
Male terminalia. (Sasakawa 2011: figs 15–18) Surstylus long, thin and sharply angled on distal 1/3 with ventral margin of bent portion with tubercle-like setae on inner surface; outer surface mostly bare with setae clustered medially. Cerci small, short-haired and slightly divergent apically. Pregonite membranous with four setulae. Postgonite small and weakly sclerotized with several setulae. Basiphallus apparently medially divided with apical U-shaped section. Epiphallus not evident. Distiphallus narrow, upcurved, apically tapered and desclerotized along midline basally and medially; sclerotized oprtions minutely spinulose; paraphallus subequal to distiphallus, tapered apically and minutely spinulose along anterior surface.
Holotype: THAILAND. Chiangmai: Doi Suthep, 28–31.iii.1958, T.C. Maa [Type No. 17245] (1♂ BPBM).
Paratype: THAILAND. Chiangdao, 5–11.iv.1958, T.C. Maa (1♂, BPBM).
Comments. The genus Sobarocephala is characterized by a two-segmented phallus composed of a short basiphallus connecting the phallapodeme to the usually rod-like and well-developed distiphallus. In S. geniculata, however, there appears to be a third intermediary segment treated by Sasakawa (2011) as the mesophallus is present—this structure is here interpreted as a distal segmentation of the basiphallus because is precedes the insertion of the paraphallus, which is always distal to the basiphallus when present in other Clusiidae. In the subfamily Clusiinae, a “mesophallus” is sometimes present due to a medial bending and breakage of the distiphallus.
Apart from segmented basiphallus and the highly unusual distiphallus and surstylus, the genitalia of Sobarocephala geniculata departs from those of other Sobarocephala in lacking both the “thumb” of the paraphallus and the “basal shield” of the distiphallus. These throw doubt on its membership in the genus, which is entirely defined by these two characters, although like most Sobarocephala (and the related genus Procerosoma Lonsdale & Marshall), cell bm is open. Externally, the notal pattern is also unique, while the dimensions of the gena and frons and structure of the paraphallus are characteristic of some Allometopon, and generic placement should be reconsidered when better-preserved material becomes available.
description: Published as part of Lonsdale, Owen, 2014, Revision of the Old World Sobarocephala (Diptera: Clusiidae), pp. 211-240 in Zootaxa 3760 (2) on pages 220-221, DOI: 10.11646/zootaxa.3760.2.4, http://zenodo.org/record/229578