Anthomyza caesarea, Roháček, 2020

Roháček, Jindřich, 2020, Anthomyzidae (Diptera) of Taiwan: new species but no new records, Acta Entomologica Musei Nationalis Pragae 60 (1), pp. 269-290 : 278

The Anthomyza flavosterna group (new group)

This new group is established here for Anthomyza flavosterna and five species new to science from Taiwan, i.e. Anthomyza caesarea sp. nov. and A. elongata sp. nov. described below, and three additional unnamed species, A. sp. nov. near elongata, A. sp. nov. (1) near flavosterna and A. sp. nov. (2) near flavosterna. The group is characterized as follows: head distinctly angular in profile; vti very long (by far the longest cephalic seta); 3 relatively weak ors becoming shorter anteriorly; thorax sparsely grey microtomentose and relatively shining; sternopleuron more or less (at least its ventral corner) yellow; f1 with very short ctenidial spine; male f2 and f3 with posteroventral row of fine erect setae, some in distal third of f3 shortened and thickened; male cercus relatively small; epandrium with anal fissure small; pregonite low, projecting little ventrally, with anterior and posterior clusters of long setae; postgonite without seta or setula; base of slender phallapodeme symmetrical; phallophore elongate; saccus small, with dense short spines; filum very robust and expanded distally, with finely tuberculate surface and slender, characteristically projecting apex; female T7+S7 with T7 extended ventrally to surround ligulate to linear (weakly sclerotized to membranous) remnant of S7; paired internal sclerites in genital chamber simplified and submembranous, situated more anteriorly than annular sclerite; annular sclerite widened, with thickened sides; spermathecae very small compared to ventral receptacle, suboval to pyriform, with transversely striated surface and at most slightly depressed apex; spermathecal ducts very long; ventral receptacle with characteristic dilated middle part and slender vermicular distal part with apex shortly twisted. At least some of these are unique apomorphies of this group, e.g. postgonite without seta or setula, distinctive construction of filum of distiphallus (with tuberculate surface) or characteristically formed ventral receptacle.

The phylogenetic relationships of A. flavosterna have been discussed several times in the past on the basis of morphological data (SUൾYƟඌIJı & RƟIJǍěൾĸ 2003; RƟIJǍěൾĸ 2006, 2009; RƟIJǍěൾĸ & BARƂൾR 2016), and, most recently, by means of molecular methods (RƟIJǍěൾĸ et al. 2019) but the results have not been consistent. Even the hypotheses obtained by means of different methods of molecular analysis (RƟIJǍěൾĸ et al. 2019) have not been in agreement as regards the phylogenetic position of A. flavosterna . The most recent morphological analysis has suggested its affinity to the A. bellatrix group (RƟIJǍěൾĸ & BARƂൾR 2016: 381 and fig. 605) as did the molecular hypothesis obtained using a maximum likelihood method, although the support of this sister-group relationship was poor in the latter (RƟIJǍěൾĸ et al. 2019: 753, fig. 2b). However, the two species recently described from China, viz. A. ornata Roháček, 2018 and A. sulphurea Roháček, 2018, could also be candidates for closer relationship not only with the A. bellatrix group (as suggested by RƟIJǍěൾĸ 2018: 70) but also with the A. flavosterna group. To clarify this affinity, more representatives of the A. flavosterna group, A. bellatrix group, and some of the above Chinese species must be obtained to expand the Anthomyza dataset for a new molecular data analysis.