Adelphydraena spinosa, 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 : 39-47

Adelphydraena spinosa , new species

Figs 1 , 7 , 13 (habitus), 9 (aedeagus), 11 (spermatheca and ventrite), 14 (map), 15 (habitat)

Type material. Holotype (male): “ GUYANA, Region XIII, 5º 0.671’N 59º 38.202’W, 524 m, Upper Potaro Camp 1 (c. 7 km NW Chenapau), Potaro margin trail; leaf packs in rocky stream; leg. Short & Baca; 11.iii.2014, GY14- 0311-05A” ( SEMC) . Paratypes (5): Same data as holotype (1 male, 1 female SEMC); Upper Potaro Camp 1 (c. 7 km NW Chenapau), stream nr. camp; gravel/sandy stream w/ detritus; 5º 0.673’N 59º 38.358’W, Short, Salisbury, La Cruz, GY 14-0314-01A (3 females, SEMC and MCZ) .

Differential diagnosis. Differentiated from other Adelphydraena by the combination of the chordate pronotum with tumidities almost totally separated by punctures in midline, the elytra with serrate margins, which are posteriorly produced in sharp processes, the labrum with a spinose process on each apicolateral angle, the comparatively large metaventral plaques, which are very narrowly separated anteriorly, and the aedeagus ( Fig. 9 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.68/0.88; head width 0.44; pronotum 0.42/0.69, PA 0.52, PB 0.53; elytra 1.04/0.88. Habitus as illustrated ( Fig. 7 ). Color: Dorsum brown to reddish brown, legs and maxillary palpi testaceous. Head: Frons finely punctate, 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 dull, strongly microreticulate. Labrum slightly longer than clypeus; median emargination setose, length nearly 0.66x labrum length; each apicolateral angle produced in minute sharp process. Eyes small in dorsal aspect, width ca. 1/6 interocular distance. Mentum densely micropunctulate, elongate, narrowed anteriorly, lobe on each side of apicomedian emargination curved ventrally and toward midline; apical width 0.5x basal width. Genae without posterior ridge. Pronotum: Pronotum subcordiform. Posterior 0.5 of disc with raised, rounded relief on each side of midline, reliefs separated anteriorly by ca. 10 large punctures, reliefs narrowly confluent along posterior margin; reliefs very shiny, very finely, sparsely punctate, punctures similar to those of frons. Reliefs bordered laterally and posteriorly by very coarse and dense punctures. Punctures bordering anterior margin smaller, more-or-less forming row on each side; punctures between row and anterior margin of pronotum much smaller, interstices shiny, 0.5–1.0x puncture diameter.All interstices anterior to discal reliefs with extremely sparse, very fine micropunctures similar in size to those of discal reliefs. Lateral depressions coarsely densely punctate. Lateral margin denticulate on anterior 1/2. Anterior margin distinctly trisinuate. Posterior margin straight. Elytra: Each elytron with 9 complete rows of punctures, tenth row represented by few punctures anteriorly; punctures on disc smaller than largest punctures on pronotal disc. Intervals raised slightly, shiny, 2–4x puncture diameter. Punctures in anterior 0.5 of rows 1–5 larger than on remainder of elytron, interstices 1–2x puncture diameter. Raised humeri connected with slightly produced anterior angles. Lateral margin strongly arcuate, serrate; serrations produced as 3–4 short sharp spines in ca. posterior ¼ of each elytron; explanate margin well developed, at midlength ca. 2x distal width of metatibia. Prosternum with midlongitudinal ridge from anterior margin to between coxae. Prosternal intercoxal process as wide as mesosternal intercoxal process; prosternal midline length ca. 2x prosternal intercoxal process width. Prosternal postcoxal process concave between submedian carinae. Mesoventrite: intercoxal process length 0.5x width, apex very slightly, if at all, arcuate. Submedian carinae attaining thickened anterior border of metaventrite. Metaventrite: with plaques well developed, slightly raised, together forming nearly complete inverted V-shape, except narrowly separated at anterior extremes ( Fig. 13 ). Submedian and sublateral low carinae extended from anterior margin to near posterior margin of metaventrite. Abdomen: Distance separating coxal cavities slightly wider than mesoventral intercoxal process width, ratio ca. 5/4. Submedian carinae of first sternite terminated slightly before posterior border of first sternite, distance separating carinae at posterior extreme ca. equal midline length of first sternite plus fused intercoxal sternite. Sternites 1–5 with hydrofuge pubescence; hydrofuge pubescence distinctly longer between carinae of first sternite than laterally and longer than on sternites 2–5; sternites 6 and 7 shiny, sparsely pubescent. Aedeagus and spermatheca as illustrated ( Figs. 9 , 11 ). Legs: without apparent modifications. Flight wings: Fully developed.

Etymology. The name is an adjective referring to the spines of the labrum and elytra.

Figures

FIGURE 1. Dorsal habitus of Adelphydraena species.

FIGURE 7. Adelphydraena spinosa n. sp., habitus of holotype.

FIGURE 13. Ventral habitus of Adelphydraena species.

FIGURES9–10.9.Adelphydraenaspinosan.sp.,holotypeaedeagus.10.AdelphydraenaorchymontiPerkins,non-type,aedeagus.

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