Desmopachria convexa group

Miller, Kelly B., 2020, Two new species of Desmopachria Babington, 1841 in the D. convexa species group (Coleoptera, Adephaga, Dytiscidae, Hydroporinae, Hyphydrini), ZooKeys 923, pp. 65-77 : 65

The Desmopachria convexa group

Diagnosis.

The Desmopachria convexa group is characterized in the genus by an articulable subapical process on the male lateral lobe of the aedeagus and the male median lobe either apically bifid (e.g., Fig. 15 ) or trifid (e.g., Fig. 11 ) with the exception of D. pilosa Miller (apically simple, Fig. 52 ) and D. majuscula Young (seemingly absent, Fig. 34 ). The species are extremely similar to each other in external appearance, though there are some diagnostic variations in size, shape, punctation and coloration. But externally there are often few particularly useful characters for distinguishing closely related species. Males and females are externally extremely similar, as well.

There are two apparent subgroups in the D. convexa species group, those with a smaller subapical articulable appendage on the lateral lobe not extending beyond the truncate apex (e.g., Figs 4 , 5 ) and those with a larger subapical articulable appendage that is leaf-like and extends well beyond the elongate, slender oblique apex of the lateral lobe (e.g., Figs 9 , 10 ). These are referred to here as the D. convexa-convexa subgroup (with the larger subapical articulable appendage) and D. convexa-signata subgroup (with the smaller subapical articulable lobe). Desmopachria convexa-convexa species are found in North and Central America and the Caribbean, and D. convexa-signata species are found in South America. It is not clear at this time how these two groups might be related to each other or their monophyletic status, but they seem to be well-characterized by the shared articulable appendage of the male lateral lobes which is unique in Desmopachria and Dytiscidae in general.

Comments.

This group corresponds to the Desmopachria convexa-grana group of Young (1980), which he later revised ( Young 1981). Additional new species were described by several investigators ( Braga and Ferreira-Jr. 2010; Miller 2001; 2005; Young 1990).

It is possible that several other described species may belong to this species group including D. attenuata Régimbart, 1895 ( Young 1980), D. balfourbrownei Young, 1990, D. striga Young, 1990, and D. subfasciata Young, 1990 based on illustrations suggesting the presence of a subapical or apical articulable structure on the lateral lobe ( Miller 2001). These species have not been well-described making the diagnostic characteristics of the group hard to discern. It does not appear that these species correspond with either of the new species described here, however.

Figures

Figures 11 - 36. Desmopachria species, male genitalia. 11, 12 D. aspera 11 dorsal aspect 12 right lateral lobe, right lateral aspect 13, 14 D. cenchramis 13 dorsal aspect 14 right lateral lobe, right lateral aspect 15 - 17 D. challeti 15 median lobe and right lateral lobe, dorsal aspect 16 median lobe, right lateral aspect 17 right lateral lobe, right lateral aspect 18, 19 D. ciruclaris 18 dorsal aspect 19 right lateral lobe, right lateral aspect 20, 21 D. aspera 20 dorsal aspect 21 right lateral lobe, right lateral aspect 22, 23 D. defloccata 22 dorsal aspect 23 right lateral lobe, right lateral aspect 24, 25 D. glabella 24 dorsal aspect 25 right lateral lobe, right lateral aspect 26, 27 D. grana 26 dorsal aspect 27 right lateral lobe, right lateral aspect 28, 29 D. isthmia 28 dorsal aspect 29 right lateral lobe, right lateral aspect 30, 31 D. laesslei 30 dorsal aspect 31 right lateral lobe, right lateral aspect 32, 33 D. lewisi 32 dorsal aspect 33 right lateral lobe, right lateral aspect 34 D. majuscula, dorsal aspect 35, 36 D. tarda 35 dorsal aspect 36 right lateral lobe, right lateral aspect. Redrawn from Young (1981).

Figures 37 - 57. Desmopachria species. 37 - 41 D. cavia 37 habitus 38 last abdominal ventrite 39 - 41 male genitalia 39 male genitalia, dorsal aspect 40 male genitalia, ventral aspect 41 male genitalia, dorsal aspect with coverslip 42 - 46 D. manus 42 habitus 43 last abdominal ventrite 44 - 46 male genitalia 44 male genitalia, dorsal aspect 45 male genitalia, ventral aspect 46 male genitalia, dorsal aspect with coverslip 47 - 51 D. varzeana 47 habitus 48 last abdominal ventrite 49 - 51 male genitalia 49 male genitalia, dorsal aspect 50 male genitalia, ventral aspect 51 male genitalia, dorsal aspect with coverslip 52, 53 D. pilosa, male genitalia 52 dorsal aspect 53 right lateral aspect 54 D. signata, male genitalia, dorsal aspect 55 - 57 D. signatoides, male genitalia 55 median lobe and left lateral lobe, dorsal aspect 56 median lobe, right lateral aspect 57 right lateral lobe, right lateral aspect. 37 - 51 Redrawn from Braga and Ferreira-Jr. (2010) 52, 53 redrawn from Miller (2005) 54 redrawn from Young (1990) 55 - 57 redrawn from Miller (2001). Scale bars: 1.0 mm (37, 42, 47); 0.5 mm for (38, 43, 48).

Figures 1 - 10. Desmopachria species. 1 - 5 D. manco 1 habitus 2 - 5 male genitalia 2 male median lobe, right lateral aspect 3 male median lobe, ventral aspect 4 male left lateral lobe, ventral aspect 5 male left lateral lobe, left lateral aspect 6 - 10 D. mortimer 6 habitus 7 - 10 male genitalia 7 male median lobe, right lateral aspect 8 male median lobe, ventral aspect 9 male left lateral lobe, ventral aspect 10 male left lateral lobe, left lateral aspect. Scale bars: 1.0 mm (1, 6).