Hydraena (Hydraenopsis) panbrevis, Perkins, 2023

Perkins, Philip D., 2023, New Neotropical and Nearctic species of water beetles in the genera Hydraena Kugelann and Ochthebius Leach, a key to North American genera and subgenera of the family, new distribution records, and a synopsis of ecology, behavior and morphology related to aquatic life (Coleoptera: Hydraenidae), Zootaxa 5367 (1), pp. 1-86 : 45-47

Hydraena (Hydraenopsis) panbrevis , new species

Figs. 2 (habitus comparison), 26 (habitus and aedeagus)

Type Material. Holotype (male): “ PANAMA: Canal Zone Barro Colorado Is., February 12, 1976 A. Newton // wet leaves and flood debris, forest stream” ( FMNH) . Paratypes (27): Same data as holotype (4 FMNH) ; same locality, leaf litter, stream edge, 5 February 1976, leg. A. Newton (8 FMNH) ; same locality, wet leaves and flood debris, forest stream, 6 February 1976, leg. A. Newton (7 FMNH) ; Canal Zone , 12.0 mi. NW Gamboa, Rio Agua Salud, (9°9.1’N, 79°44.2’W), flood debris along river, 19.ii.1976, leg. A. Newton (6 FMNH) ; 6.7 mi. NW Gamboa , (9°9.1’N, 79°44.2’W), flood debris along river, 15.vi.1976, leg. A. Newton (1 FMNH) ; 6.7 mi. NW Gamboa, Rio Mendosa , (9°9.1’N, 79°44.2’W), flood debris along river, 19.ii.1976, leg. A. Newton (1 FMNH) .

Differential Diagnosis. This new species, which is a member of the H. marginicollis Subgroup (see Perkins 1980: 69), can be differentiated from others by the combination of the very small body size (ca. 1.12 mm), the rather broad form, the pronotum with dark brown macula surrounded by wide light brown margins, the wide and short mesoventral intercoxal process (l/w ca. 1/1), the very thin metaventral plaques (ratios of P2/w/l/s ca. 1/0.1/1/1.1), and the aedeagus ( Fig. 26 ). The aedeagus cannot be favorably compared with any other known New World Hydraena .

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.12/0.52; head width 0.30; pronotum 0.24/0.41, PA 0.33, PB 0.36; elytra 0.71/0.52. Habitus as illustrated ( Fig. 26 ). Dorsum of head with frons dark brown, clypeus light brown; pronotum with dark brown macula surrounded by wide light brown margins; elytra brown; palpi testaceous, tip of last palpomere not darker. Dorsum of head and pronotum very finely very sparsely punctulate, more sparsely punctulate on macula than on surrounding areas, interstices strongly shining; punctures of frons disc and pronotal disc ca. 1xef, interstices on pronotal disc ca. 3–4xpd; punctures of clypeus very fine, lateral areas microreticulate. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral pronotal fovea shallow, other usual foveae exceedingly shallow or absent.

Elytra with summit of posterior declivity slightly beyond midlength; lateral explanate margins narrow; on basal 1/3 punctures slightly larger than largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, width ca. 1–2xpd, as are interstices between punctures of a row.Apices in dorsal aspect conjointly, rather sharply rounded, in posterior aspect margins forming very shallow angle with one another.

Venter: Mentum very sparsely very finely punctulate; postmentum very finely densely micropunctulate. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.1/1/1.1. P1 rather wide; median carina sinuate in profile. P2 wide and short, l/w ca. 1/1, sides parallel, apex blunt, apex raised slightly above mesoventral intercoxal process. Plaques very thin lines, almost obsolete, straight, anteriorly convergent, not raised, located at sides of deep median depression. AIS concave, width at arcuate posterior margin ca. 1.2x P2. All tibiae slender, straight. Abdominal apex symmetrical; last tergite with apicomedian notch.

Distribution. Currently known only from Panama.

Etymology. Named in reference to the geographical distribution and the very small body size, the very short and wide mesoventral intercoxal process, and the very short aedeagal parameres.

Figures

FIGURE 2. Dorsal habitus of Hydraena species.

FIGURE 26. Hydraena (Hydraenopsis) panbrevis, new species, holotype habitus and aedeagus.