Adelphydraena surinamensis, Perkins & Ribera, 2020

Perkins, Philip D. & Ribera, Ignacio, 2020, Three new species and DNA sequence data of the rare South American water beetle genus Adelphydraena Perkins, 1989 (Coleoptera: Hydraenidae), Zootaxa 4858 (1), pp. 35-52 : 47-51

Adelphydraena surinamensis , new species

Figs 1 , 8 , 13 (habitus), 6 (aedeagus), 6 (last tergite), 12 (spermatheca and ventrite), 14 (map)

Type Material. Holotype (male): “ SURINAME: Brokopondo, Brownsberg Nature Park, Leo Val , (4°57’16.0812’’N, 55°11’26.8224W)’’, 23.iii.2017, Leaf packs and detritus at back of waterfall, leg. Baca et al., SR-0323-01C” ( SEMC) . Paratype: Same data as holotype (1 female, SEMC) .

Differential diagnosis. Differentiated from other Adelphydraena by the combination of the small size (ca. 1.40 mm), the chordate pronotum with denticulate lateral margins, and tumidities partially separated by punctures in midline, the elytra with serrate margins, the short metaventral plaques, and the aedeagus ( Fig. 6 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.40/0.72; head width 0.40; pronotum 0.34/0.62, PA 0.47, PB 0.38; elytra 0.83/0.72. Habitus as illustrated ( Fig. 8 ). Color: Brown-testaceous. Head: Frons finely punctate on slightly tumid disc, punctures smaller than eye facets; shiny in middle, microreticulate and dull laterally; posterior line not extended forward at juncture of shiny and microreticulate areas. Clypeus strongly microreticulate. Labrum slightly longer than clypeus; median emargination setose, deep, length ca. 0.75x labrum length; apicolateral angles each with very small spinose projection. Eyes small in dorsal aspect, width 0.25x interocular distance. Mentum elongate, narrowed anteriorly, lobe on each side of apicomedian emargination curved ventrally and toward midline; apical width 0.75x basal width. Genae without posterior ridge. Pronotum: Pronotum subcordiform. Posterior 0.5 of disc with transverse, raised, rounded relief, larger laterally than in midline, relief margin anteromedially with two large punctures side-by-side, relief submedially with two smaller punctures, one behind other, on each side; relief very shiny, very finely, sparsely punctate, punctures similar to smallest punctures of frons. Punctures posterior to relief very coarse and dense, forming transverse rows, two laterally, three medially, punctures nearly confluent, interstices narrow walls or nearly so. Punctures along anterior margin of discal relief coarse, forming row; punctures anterior to row smaller than those of row and posterior punctures, shallow, bottoms apparently flat with central seta, interstices shiny, 0.51–1.0x puncture diameter.All interstices anterior and posterior to discal relief with extremely sparse, very fine punctures similar in size to those of discal relief. Lateral depressions subrugulose, with punctures of varying sizes. Lateral margin denticulate, more distinctly so anterior to middle. Anterior margin weakly trisinuate. Posterior margin weakly bisinuate, nearly straight. Elytra: Each elytron with 9 complete rows of punctures, tenth row represented by few punctures anteriorly; punctures on disc ca. 1x punctures on anterior area of pronotal disc, or slightly larger. Intervals raised slightly, shiny, 2–3x puncture diameter. Punctures in anterior 0.5 of rows 1–5 slightly larger than on remainder of elytron, interstices 1–2x puncture diameter. Raised humeri connected with slightly produced anterior angles. Lateral margin strongly arcuate, explanate margin well developed, at midlength slightly wider than distal width of metatibia. Lateral margins serrate, more strongly so in anterior than posterior 0.5. Prosternum: Prosternal intercoxal process as wide as mesoventral intercoxal process; prosternal midline length 2x prosternal intercoxal process width. Prosternal postcoxal process flat between submedian carinae. Mesoventrite: Mesosternal intercoxal process length ca. 1x width, apex straight; submedian carinae attaining thickened anterior border of metasternum. Metaventrite: Plaques well developed ( Fig. 13 ). Abdomen: Distance separating coxal cavities ca. 2x mesoventral intercoxal process width. Submedian carinae of first ventrite terminated slightly before posterior border of first ventrite, distance separating carinae at posterior extreme slightly greater than midline length of first ventrite plus fused intercoxal ventrite. Ventrites 1–5 with hydrofuge, ventrites 6 and 7 shiny, sparsely pubescent. Aedeagus and spermatheca as illustrated ( Figs. 6 , 12 ). Legs: All legs without apparent modifications. Flight wings: Fully developed.

Etymology. The name is an adjective referring to the geographical distribution.

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Figures

FIGURE 1. Dorsal habitus of Adelphydraena species.

FIGURE 8. Adelphydraena surinamensis n. sp., habitus of holotype.

FIGURE 13. Ventral habitus of Adelphydraena species.

FIGURES 5–6. 5. Adelphydraena spangleri Perkins, non-type aedeagus and last tergites. 6. Adelphydraena surinamensis n. sp., holotype aedeagus and last tergite.

FIGURES 11–12. 11. Adelphydraena spinosa n. sp., spermatheca and terminal abdominal segments. 12. Adelphydraena surinamensis n. sp., spermatheca and terminal abdominal segments.