APSILOCEPHALIDAE

Grimaldi, David A., 2016, Diverse Orthorrhaphan Flies (Insecta: Diptera: Brachycera) In Amber From The Cretaceous Of Myanmar: Brachycera In Cretaceous Amber, Part Vii David A. Grimaldi, Bulletin of the American Museum of Natural History 2016 (408), pp. 1-132 : 76

FAMILY APSILOCEPHALIDAE

This is a small, highly relict family with three genera and four species in the extant fauna that have widely disjunct distributions: Apsilocephala longistyla Kröber in the southwestern United States and Mexico; Clesthentia aberrans White , in New Zealand, C. crassioccipitus (Nagatomi et al.) in Tasmania; and Kaurimyia thorpei Winterton and Irwin in New Zealand. Clesthentiella Nagatomi et al. were synonymized under Clesthentia by Winteron and Irwin (2008). Cretaceous fossils include Burmapsilocephala cockerelli Gaimari and Mostovski in Cretaceous Burmese amber (see below), and a new species of Burmapsilocephala described below, also in Burmese amber. Tertiary species are Apsilocephala vagabonda (Cockerell) , in Late Eocene shale from Florissant, Colorado (originally described in Rueppellia [ Therevidae ], transferred by Hauser and Irwin, 2005); and Apsilocephala pusilla (Hennig) in Eocene Baltic amber (originally described as “ Psilocephala ” [ Therevidae ] and transferred to Apsilocephalidae by Hauser, 2007). Apsilocephala pusilla is the most common therevoid fly in Baltic amber. Gaimari and Mostovski (2000) mentioned an undescribed species of Apsilocephala in Baltic amber. The therevoid fly Kumaromyia burmitica Grimaldi and Hauser in Burmese amber was considered a possible apsilocephalid (Grimaldi et al., 2010) and this identity was adopted elsewhere ( Winterton and Ware, 2015 [).

Apsilocephalidae is in the therevoid clade of Asiloidea , the family first erected by Nagatomi et al. (1991a). Later, however, Nagatomi and Yang (1998) synonymized Apsilocephalidae under the Mesozoic family Rhagionempididae , a change that has never been adopted by other dipterists. Placement of Apsilocephala within the therevoid clade has been confirmed by several phyloge- netic studies, possibly as the sister group to Therevidae ( Yeates et al., 2003; Trautwein et al., 2010), although evidence is strong that it is closely related to the monotypic Chilean family Evocoidae ( Wiegmann et al., 2011; Winterton and Ware, 2015; Winterton et al., 2016).

Genus Burmapsilocephala Gaimari and Mostovski

Burmapsilocephala Gaimari and Mostovski, 2000: 43 .

EMENDED DIAGNOSIS: Separated from the extant genus Apsilocephala by the fossil genus having a longer aristalike terminal article of the flagellum; one postpronotal macroseta (vs. none); scutellum with one pair of macrosetae (vs. two); vein R 5 ends near or at the wing tip (vs. ventrally); dorsocentral setae lacking.

TYPE SPECIES: Burmapsilocephala cockerelli Gaimari and Mostovski, 2000 . In Burmese amber.

COMMENTS: The genus was described by Gaimari and Mostovski (2000) on the basis of a well-preserved female specimen in the Burmese amber collection of the Natural History Museum, London. As discussed by them, the body is very similar to that of Apsilocephala longistyla , with differences as noted in the diagnosis above, although Burmapsilocephala are considerably more gracile than the common Apsilocephala pusilla in Baltic amber. Also, the male genitalia of a new species of Burmapsilocephala , described below, bear little resemblance to that of the living species A. longistyla or A. pusilla in Baltic amber (which are quite similar). The male genitalia of living Apsilocephala (possibly several species) have been thoroughly studied, with descriptions and illustrations provided by Nagatomi et al. (1991b), Sinclair et al. (1994), and Yeates (1994). The male genitalia of Burmapsilocephala are considerably simpler than in Apsilocephala , the former lacking the pair of large bristles on the gonocoxa; the large “apical coiled tube” ( Nagatomi et al., 1991b) (phallus) is not apparent; the gonocoxae and gonostyli are free and articulating (not fused to epandrium); epandrium (tergite 9) is not simple and entire but rather fully separated medially; cerci are small lobes between the epandrial lobes and gonocoxae. Indeed, the bisected epandrium and small cercal lobes are very similar to the condition in another relict, long-legged gracile asiloid, Evocoa (Evocoidae) ( Yeates et al., 2003). Evocoa , however, have a substantially different wing from that of Apsilocephala and Burmapsilocephala , with Evocoa having lost M 3 and cell m3, cell cup is open (CuP and A 1 are not even convergent), and the wing base is petiolate. Interestingly, Evocoidae and Apsilocephalidae are probably living sister groups, so the genitalic resemblance is probably based on close relationship of the two families.