Desmopachria nitida, Babington, 1841

Miller, Kelly B. & Wolfe, G. William, 2018, Nine New Species in the Desmopachria nitida Species-Group of the Neotropical Genus Desmopachria Babington, 1841 (Coleoptera: Adephaga: Dytiscidae: Hydroporinae: Hyphydrini), The Coleopterists Bulletin 72 (1), pp. 97-112 : 98-100

Desmopachria nitida species-group

Diagnosis. Members of the D. nitida speciesgroup are characterized by male lateral lobes that are apically distinctly bifid, usually with each ramus elongate (e.g., Figs. 3, 7 ). Many also have the median lobe apically bispinous (e.g., Figs. 6, 13 ), though this is variable with that of some species being extremely complex and even asymmetrical (e.g., Fig. 22 ). Members of the D. nitida speciesgroup are very similar to those in the D. convexa species-group. Members of both groups are characterized by small size, spherical shape, and usually lack of maculation. It is often exceptionally difficult to distinguish among species (or even sexes) externally but the male genitalia are distinctive.

Comments. The D. nitida species-group was placed in Desmopachria sensu stricto by Young (1980), though at the time it had only a single species. Later new species were added by Young (1986, 1989, 1990a), Miller (1999, 2005), and Braga and Ferreira-Jr. (2014). Additional previously described species were also added to the group by Miller (2001). Members of this species-group are similar externally. In fact, among these new species, there were few useful external diagnostic features discovered except for some size differences and coloration with some species distinctly dorsally maculate, but most are more evenly colored. Even males and females are difficult to distinguish externally. Because of the extreme similarity of many of the species, they are collectively described here, and the species accounts only include coloration, diagnostic features (mainly male genitalia), and measurements.

Two species that were described by Mahkan (2012, 2015), though inadequately, may belong to this group, Desmopachria aschnae Mahkan, 2012 and Desmopachria barackobamai Mahkan, 2015 . The first, D. aschnae , most clearly does, though Mahkan did not explicitly assign the species to the D. nitida species-group. That said, the description and the photographs are, unfortunately, inadequate to determine the species. Given the apparent width of the male median lobe in ventral aspect, D. aschnae may refer to Desmopachria hardyae Miller and Wolfe , new species, but the two species seem to have different lengths of the apical rami of the lateral lobes. The dorsal ramus is apparently much longer than the ventral ramus in D. aschnae (fig. 4, Mahkan 2015) than it is in D. hardyae ( Figs. 16, 17 ). Desmopachria barackobamai is even less clearly assigned to the D. nitida species-group. Although Mahkan (2012, 2015) indicated the holotypes were deposited in the Department of Entomology at the University of Suriname, attempts to locate the specimens were unsuccessful. The apparent loss of type material combined with the inadequate details in the descriptions and photographs in the original descriptions means these species remain ambiguous.

Based on published descriptions and illustrations of males, it is possible that additional described species belong to this group. For example, Desmopachria attenuata Régimbart , Desmopachria balfourbrownei Young , and Desmopachria striga Young may belong to the D. nitida species-group (bifid lateral lobes) or the D. convexa species-group (lateral lobes with an articulated process laterally) ( Miller 2001).

Description. Body shape: Short, broad, very broadly oval in dorsal aspect, body outline nearly continuously curved along lateral margins of head, pronotum, and elytron, lateral margin of pronotum slightly more strongly curved than overall body outline; dorsoventrally somewhat compressed. Sculpture and structure: Head broad, short; anterior margin of clypeus distinctly margined with continuous narrow bead; surface of head shiny, very finely and sparsely punctate; eyes large (HW/EW = 1.8–2.3); antennae short, antennomeres III–X short, moderately broad, antennomere XI elongate, apically pointed. Pronotum short, broad, laterally distinctly curved with continuous narrow bead; surface shiny, very finely and sparsely punctate, without basal striae. Elytron broad, laterally broadly curved; surface shiny, very finely and sparsely punctate, without basal or sutural striae or other striae or tumidities. Prosternum short, longitudinally compressed; prosternal process elongate, without medial ventral tubercle, apically moderately broad, concave, apically sharply pointed. Metaventrite broad and evenly smoothly convex medially, surface shiny, impunctate; metathoracic wings extremely slender. Metacoxa with medial portion short, less than half length of metasternite medially, metacoxal lines straight, slightly divergent anteriorly; lateral portion of metacoxa very large, anteriorly strongly expanded; surface shiny, very finely and sparsely punctate. Metatrochanter very large, subequal to length of ventral margin of metafemur; legs otherwise not noticeably modified. Abdomen with surfaces shiny and smooth, very finely and sparsely punctate.

Figures

Figs. 1–32. Male genitalia of Desmopachria species in the D. nitida species-group. D. curseenae: Median lobe – 1) Right lateral aspect; 2) Ventral aspect; Right lateral lobe – 3) Right lateral aspect; 4) Ventral aspect. D. delongi: Median lobe – 5) Right lateral aspect; 6) Ventral aspect; Right lateral lobe – 7) Right lateral aspect; 8) Ventral aspect. D. gingerae: Median lobe – 9) Right lateral aspect; 10) Ventral aspect; 11) Right lateral lobe, right lateral aspect. D. gyrationi: Median lobe – 12) Right lateral aspect; 13) Ventral aspect; 14) Right lateral lobe, right lateral aspect. D. hardyae: Median lobe – 15) Right lateral aspect; 16) Ventral aspect; 17) Right lateral lobe, right lateral aspect. D. kemptonae: Median lobe – 18) Right lateral aspect; 19) Ventral aspect; Right lateral lobe – 20) Right lateral aspect; 21) Ventral aspect. D. lloydi: 22) Median lobe, ventral aspect; 23) Apices of median lobe, anterior aspect; Right lateral lobe – 24) Right lateral aspect; 25) Ventral aspect. D. singhae: Median lobe – 26) Right lateral aspect; 27) Ventral aspect; 28) Right lateral lobe, right lateral aspect. D. vohrae: Median lobe – 29) Right lateral aspect; 30) Ventral aspect; Right lateral lobe – 31) Right lateral aspect; 32) Ventral aspect.