Stenocyamops Papp

Grimaldi, David A., 2009, The Asteioinea of Fiji (Insecta: Diptera: Periscelididae, Asteiidae, Xenasteiidae), American Museum Novitates 3671, pp. 1-60 : 27

Genus Stenocyamops Papp

Stenocyamops Papp et al., 2006: 216 . Type species: S. thaii Papp , by original designation.

DIAGNOSIS (revised): Small flies with many of the distinctive features of Stenomicra (above), except these are slightly larger, more robust, dark bodied, and with the anepisternum having silvery microtomentum and a row of fine setae on posterior margin; vein A 1 +CuA 2 present; anal lobe and alula present but highly reduced; male terminalia entirely symmetrical. The Fiji species have, in addition, a setose epandrium, cerci with a pair of pendulous ventral lobes, and a reduced hypandrium that is divided in the center.

COMMENTS: Stenocyamops was described on the basis of a unique male specimen collected in Doi Phuka National Park, Thailand ( Papp et al., 2006), and the genus erected and named because of a morphology that is apparently transitional between Stenomicra and Cyamops . Here, four new, closely related species are added to this genus, suggesting that numerous species remain to be discovered throughout Asia and the Pacific. The Fiji species all seem closely related and perhaps are a monophyletic group, but until there is much better sampling throughout the Indo-Pacific it will be impossible to determine whether this is an endemic lineage.

Like Cyamops , the Fiji Stenocyamops are significantly larger (0.64–0.74 mm ThL), more robust, and darker than typical Stenomicra , which are smaller (0.53–0.60 mm ThL), slen- der, and flat, light-colored flies. Also, Stenocyamops possesses an anal lobe (though smaller than in Cyamops ), which is virtually lost in Stenomicra , particularly in the subgenus Podocera . Many Cyamops possess a silveryreflective microtomentum on the face, frontoorbital plates, cheeks, and anepisternum, which Stenocyamops also have (though not on the face or FOPs; the Fiji species of Stenocyamops further have a row of fine setae on the posterior margin of the anepisternum; some Cyamops have a few setae in this region). Stenocyamops lacks several of the distinctive apomorphic features of Cyamops , namely: loss of the pair of inner vertical setae, possession of a pair of ‘‘inner’’ fronto-orbital setae, ventral margins of the eyes that are separated by only 3–4X the facet width, and male genitalia (surstyli, hypandrium) that are highly asymmetrical.

Stenocyamops shares some apomorphic features with Stenomicra , including the following: palps highly reduced; acrostichal setulae in a single (usually incomplete) row; single pair of scutellar setae (anterior pair reduced and sometimes lost in Cyamops ); and the small basal veins CuA 2 and bm-cu lost, rendering loss of cells cup and bm, respectively (in S. thaii CuA 2 is present). Also, Stenomicra shares with at least the Fiji Stenocyamop s (the description of S. thaii being insufficient to judge) a distinctive feature of the epandrium, wherein each lateral wall has a sclerite that articulates with a condyle on the lateral apex of the hypandrium. This pair of sclerites is probably an invagination of the posterolateral margins of the epandrium. The male genitalia of Stenomicra have an asymmefotrical hypandrium; that of Stenocyamops is symmetrical.