Sclerocoelus Marshall 1995

Genus Sclerocoelus Marshall, 1995 Sclerocoelus Marshall, 1995: 283 (masculine). Type species: Limosina sordipes Adams, 1904, original designation. Sclerocoelus – Marshall 1997: 97 [diagnosis, phylogeny, key, illustrations]. — Roháček et al. 2001: 248 [world catalog]. Diagnosis Almost all Sclerocoelus species exhibit the following combination of characters: (1) very broad lunule; (2) very broad alula; (3) a proximal posterodorsal seta on the mid tibia; (4) well-developed postsutural intra-alar bristle; and (5) complex male genital pouch composed of several additional sclerites. Other diagnostic characters include (6) a midventral seta on the female mid tibia (absent in males) and (7) costa terminating at the end of R 4+5. Some species lack the proximal posterodorsal mid tibial seta (S. mandibulum sp. nov. and S. argentinensis sp. nov.), however all other diagnostic characters are present in these species. One of the brachypterous species of Sclerocoelus (S. aduncus sp. nov.) has a small alula but has all other diagnostic characters of the genus (the other brachypterous species have a very broad alula). Sclerocoelus inornatus sp. nov. and S. lutosus sp. nov. lack the distinctively sclerotized male genital pouch that characterizes other Sclerocoelus species, but they do have the other defining characters of Sclerocoelus as listed above (with the possible exception of the dimorphic mid tibia in S. inornatus, as no females are known). A morphological phylogeny (Fig. 2) suggests that the relatively simple genital pouch of these species represents a character reversal rather than a plesiomorphic trait, however neither species was available for sequencing. Redescription BODY. Colour yellow to dark brown. Length 1.8–5.3 mm. HEAD. Brown, variable portion of frons orange; face, gena, and antennae orange to brown; frontal vitta, interfrontal plate and orbital plate subshining, indistinctly microtomentose. Frontal width 2.2–2.4 × frontal height. Two or three pairs of strong interfrontal bristles usually surmounting a very fine third or fourth pair; two strong lateroclinate orbital bristles, anterior orbital 0.4–0.7 × length of posterior; ocellar bristle large and diverging; postocellar bristle small; inner and outer vertical bristles large; inner and outer occipital bristles large. Vibrissa large, vibrissal angle with one subvibrissal seta; gena with an enlarged anteroventral seta and several smaller setae. Palpus yellow to brown, clavate, with two large preapical ventral setulae. Lunule usually broad, bulging and prominent, always broader in female than male; face slightly excavated and usually short, medially about 0.3–1.5× as tall as lunule, medial keel short and usually only slightly developed. Antennae divergent; pedicel with long marginal setae; postpedicel ovoid, somewhat flattened on outer surface; arista long-pubescent. Eye variable but usually large, greatest height 1.1–5.0× shortest genal height, posteroventral corner concave from broadened gena. THORAX. Brown, scutum paler laterally. One or two (usually) distinct postsutural dorsocentral bristles, anterior pair sometimes reduced, 0.3–0.7 × length of posterior (prescutellar) pair, separated by 4–12 rows of acrostichal setulae. Two postpronotal bristles, outer bristle large and inner bristle small; two notopleural bristles, anterior slightly larger than posterior; two strong supra-alar bristles; postalar and intrapostalar bristles large; prescutellar acrostichal setulae usually enlarged (3.0–4.0 × length of anterior setulae). Prosternum linear, membrane around prosternum usually bare but sometimes with additional setulae-bearing sclerites. Katepisternum with a very fine anterior setula and a large posterior bristle. Scutellum subtriangular, 1.3× as wide as long, with four long marginal bristles in usual positions. LEGS. Brown to yellow. Fore femur with 3–5 large ventral preapical setae. Dorsal surface of mid tibia with three (one small and one large anterior and one small posterior) proximal setae and three (one small and one large anterior and one large posterior) distal setae except in male S. mandibulum sp. nov. Ventral surface of male mid tibia with an apicoventral bristle and two rows of stout setae in apical quarter to two-thirds, mid femur with two corresponding rows of stout proximal setae; ventral surface of female mid tibia with strong midventral bristle and long apicoventral bristle. Mid basitarsus with distinctly enlarged basal ventral setula. Hind tibia with stout apicoventral seta. WING. Hyaline to infuscate. CS2 0.6–1.0 × CS3. R 2+3 sinuate, basal curve almost straight and distal curve strong; R 4+5 slightly sinuate, ending just before wing tip; costa ending at or extending just beyond end of R 4+5 (1–3× costal width). M 1 extending to wing tip as distinct sinuate crease. M 4 extending past dm-m 1.1–1.3 × length of dm-m. CuA+CuP sinuate, almost reaching wing margin. Alula almost always large, ovoid. Halter pale brown to brown. MALE ABDOMEN. Dark brown, posterior edges of tergites usually slightly desclerotized. T2–5 and S2–4 long-setose with large posterolateral setae. S5 highly variable, usually rectangular; posteromedial chaetotaxy variable. Genital pouch including multiple sclerites, most of which seem to be derived from the ventral part of S6+7 (sclerites A–E, as defined in Materials and Methods). Epandrium variable, usually wedge-shaped, and uniformly long-setose; perianal pads usually weakly developed and membranous, but sometimes sclerotized and enlarged. Cercus usually weakly differentiated from epandrium, usually widely separated but sometimes entirely or partially fused medially to form subanal plate; pseudocercus usually small and separated from epandrium, sometimes fused to inner ventral corners of epandrium or entirely absent; when present, almost always with three setae. Halves of subepandrial sclerite usually strongly arched and joined medially. Subcercus usually large and complex. Hypandrium usually large; anteromedial hypandrial apodeme elongate but usually shorter than phallapodeme; lateral hypandrial arm strongly arched, separate from anteroventral corner of epandrium and usually separate from anteromedial hypandrial apodeme (fused to anteromedial apodeme in S. punensis sp. nov., S. paranebulosus sp. nov. and S. penai sp. nov.). Surstylus variable, usually larger than subcercus. Postgonite variable. Phallapodeme large, curved, sometimes dorsoventrally flattened apically; basiphallus variable, often stout with a neck-like distal part, epiphallus variably developed; distiphallus usually small, largely membranous, and supported by numerous sinuate sclerites. FEMALE ABDOMEN. Dark brown, edges of preabdominal sclerites, especially sternites, usually desclerotized. T2–6 and S2–6 uniformly long-setose with longer posterolateral setae. T7 broad, rectangular; T8 either desclerotized dorsomedially, appearing as two large lateral sclerites, or divided into pale dorsal sclerite and two dark lateral sclerites, posteromedial corners of lateral sclerites usually expanded posteriorly. Epiproct usually large, shield-like and often desclerotized along midline, appearing as two separate sclerites, usually densely setulose, almost always with pair of large dorsal setae. Cercus variable, usually elongate, always densely setulose, usually with large apical and dorsal setae. S7 broad, often pointed posteromedially, long-setose with 4–6 distinctly enlarged, preapical, posterior setae; S8 usually highly reduced, often divided into two small, lateral sclerites each with two minute sensory setulae, though sometimes with only a single large, medial sclerite or entirely membranous/absent. Hypoproct large, broad, U-shaped, densely setulose posteriorly with 5–16 distinct setae. Three or (rarely) two spermathecae, bulb various, sometimes spherical or cylindrical but asymmetrically bean-shaped in one major clade, often with 1–2 invaginations, invaginations sometimes with a finger-like, central process pointing outwards; paired spermathecae (when present) smaller than single spermatheca; ducts short. Similar and related genera Marshall & Dong (2008) noted superficial similarities between the widespread southern hemisphere genus Parasclerocoelus and some species of Sclerocoelus, including a large intra-alar bristle, sinuate R 2+3, almost straight R 4+5, a double row of stout setae on the apicoventral surface of the mid tibia, large S6–8, pruinose thorax and similar female terminalia. However, Parasclerocoelus has a narrow alula, a small lunule and no posterior proximal seta on the mid tibia. Its male genital pouch includes an arm of S6 that extends across the anterior face of the genital pouch but lacks the multiple genital pouch sclerites that define Sclerocoelus. The only species of the high Andean genus Paramosina is also externally similar to sympatric species of Sclerocoelus. Marshall & Yau (2014) noted the broad lunule and broad alula as similarities, but noted the simple male genital pouch, complete subanal plate, well-developed cerci and epiproct in the female as significant differences between the two genera. The male S6 is divided into two ventral lobes in Paramosina, but it does not break into separate pieces ventrally as in Sclerocoelus. Paramosina also differs from Sclerocoelus in lacking the posterior proximal seta on the mid tibia in both sexes and in lacking the midventral mid tibial bristle in females. Nine species of Sclerocoelus were collected along with the type series of Paramosina hirsuta Marshall, 2014 at 3600 m a.s.l. (Quebrada Mishahuaycu, Ecuador). Males of the small African genus Parapoecilosomella Papp, 2008 have a large genital pouch superficially similar to some Sclerocoelus, but the two species of Parapoecilosomella differ so widely from Sclerocoelus in wing venation and other features it seems unlikely that there is a close relationship. Marshall (2000) suggested Sclerocoelus as a possible sister group to the mostly Neotropical gen

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