Hydraena (Hydraenopsis) canalula, 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 : 15-17

Hydraena (Hydraenopsis) canalula , new species

Figs. 1 (habitus comparison), 8 (habitus and aedeagus)

Type Material. Holotype (male): “ Mexico: Mexico, NE of Temescaltepec , Rio Verde, 1830 m, 21 iv 2004, coll. William D. Shepard ” ( MCZ) . Paratypes (6): Same data as holotype (2 males MCZ); Real de Arriba Temescaltepec, Mex. vii 1932 // H. E. Hinton Collector (2 males, 2 females UKNHM) .

Differential Diagnosis. This new species is a member of the H. leechi Group, H. argutipes Subgroup ( Perkins 1980: 151) . It will key to couplet 36 in Perkins (1980: 68), along with H. bractea and H. bractoides . Reliably differentiating these three species will require dissection and careful examination of the male genitalia ( Fig. 8 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.57/0.65; head width 0.37; pronotum 0.37/0.51, PA 0.41, PB 0.44; elytra 0.94/0.65. Habitus as illustrated ( Fig. 8 ). Dorsum dark brown, palpi brown, tip of last palpomere darker. Dorsum of head and pronotum moderately coarsely moderately densely punctulate, interstices shining; punctures of frons disc ca. 1xef, those of pronotal disc ca. 2–3xef, interstices on pronotal disc quite variable, ca. 1–4xpd; punctures of clypeus very fine, lateral areas microreticulate; all dorsal punctures with short recumbent seta. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin very weakly emarginate over middle ½, almost straight, without scintilla; anterolateral pronotal fovea deep, posterolateral foveae very shallow, posteromedial foveae moderately deep.

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

Venter: Mentum very sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate in median concavity, surrounding areas smooth, shining. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/3/6/1.5. P1 laminate; median carina sinuate in profile. P2 narrow, l/w ca. 4/1, sides slightly converging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Metaventrite with midlongitudinal ridge between mesoventral intercoxal process and plaques. Plaques large, slightly raised, parallel, shining, narrowly separated by about ½ plaque width. AIS width at straight posterior margin ca. 2.5x P2. Pro- and mesotibiae straight, moderately stout. Metatibia arcuate, markedly widened on inner margin over distal 1/2. Abdominal apex symmetrical; last tergite with shallow apicomedian notch.

Distribution. Currently known only from two localities at or near Temescaltepec, State of Mexico, Mexico.

Etymology. Named in reference to the narrow canal separating the metaventral plaques.

Figures

FIGURE 1. Dorsal habitus of Hydraena species.

FIGURE 8. Hydraena (Hydraenopsis) canalula new species, holotype habitus and aedeagus.