Ochthebius (Asiobates) convexus, 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 : 36-37

Ochthebius (Asiobates) convexus , new species

Figs. 4 (habitus comparison), 21 (habitus and aedeagus)

Type Material. Holotype (male): “ MEXICO: Guanajuato, Victoria, Pto de Palmas , 1950 m, 11.viii.1999, 21°24’59’’N, 100°04’60’’W, 1462 m R. Arce Col. ” ( IEXA).

Differential Diagnosis. Members of this small, convex species will key to couplet 14 of Ochthebius (Asiobates) in Perkins (1980: 304). It is differentiated from O. apicalis Sharp by the less spindle-shaped body and the aedeagus, and from O. browni Perkins by the aedeagus and the more convex body form. Reliable determinations will include dissection of males and careful examination of the aedeagus ( Fig. 21 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.66/0.81; head width 0.45; pronotum 0.44/0.66 (width including hyaline margin), PA 0.54, PB 0.44 (PB sclerotized part); elytra 0.96/0.81. Habitus as illustrated ( Fig. 21 ). Form ovate, very convex. Pronotum and elytra dark reddish brown, dorsum of head dark brown to black; legs and palpi dark reddish brown. Frons effacedly microreticulate over entire surface; punctures coarse and dense, some confluent; interocular foveae deep and large, width of each slightly greater than distance between them; interocular tuberculi large; basomedial fovea nearly as deep as interocular foveae, slightly smaller. Frontoclypeal suture evenly arcuate. Clypeus length 0.50 width; markedly microreticulate. Labroclypeal suture straight. Labrum length 0.33 width; very finely sparsely punctate, very finely pubescent; anterior margin straight, edge very weakly upturned. Maxillary palpus with palpomere 3 moderately wide; palpomere 4 slightly less than 0.50 length of penultimate. Lateral margin of mandibles (male) with spines.

Pronotum with anterior hyaline border moderately wide in front of disc, slightly wider in front of lateral fossulae, then tapered to anterior angles. Lateral hyaline border origin at anterior angles, extended narrowly along lateral depressions, broad in region of posterior excavation, very narrow around posterior margin. Anterior margin of pronotum weakly arcuate, with excavation in front of each lateral depression; anterior angles obtuse. Lateral depressions not appearing inflated, broad, with large punctures; margins moderately arcuate, irregular; posterior extremes excavate and with small tooth; pronotum constricted behind lateral depressions. Lateral fossulae deeply impressed, coarsely punctate; inner margin abrupt, posterior extreme tapered into lateral hyaline border. Pronotal disc convex, punctures in interfoveal area large, dense, irregularly sized, separated by thin walls in anterior, some in posterior separated by ca. puncture diameter; setae absent or very indistinct; surface between punctures smooth and shiny. Median groove deeply impressed, effacedly microreticulate; anterior 0.5 much wider than posterior. Anterior foveae absent, this region with dense deep punctures. Posterior foveae large, deep.

Elytral disc with broad depression in midregion, shiny, with six rows of punctures between suture and humeri. Sides very convex, posterior declivity beginning near midlength; punctures round; intervals rounded, slightly elevated, width ca. 1–2xpd, with surface irregularities; interstices between punctures ca. 1–2xpd; setae absent or very indistinct. Explanate margin narrow. Elytral apices separately rounded.

Venter: Mentum moderately shining, with moderately dense setigerous punctures, setae short, inconspicuous except longer and denser at anterolateral angles. Prosternum hydrofuge pubescent, without median carina. Metaventrite hydrofuge pubescent laterally, with large oval moderately shining non-punctate glabrous area on disc, large, deep setigerous punctures at lateral margins of glabrous area. Abdominal ventrites 1–5 hydrofuge pubescent. Ventrite 6 shining, with sparce, short setae in posterior 1/2. Last tergite rounded apically. Protarsomeres 1–3 (male) with suction setae.

Distribution. Currently known only from the type locality.

Etymology. Named in reference to the very convex dorsum.

Figures

FIGURE 4. Dorsal habitus of species of Ochthebius.

FIGURE 21. Ochthebius (Asiobates) convexus, new species, holotype habitus and aedeagus.