Ochthebius (Aulacochthebius) mpumalangicus, Perkins, 2023

Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), Zootaxa 5228 (5), pp. 501-546 : 522

O. (Aulacochthebius) mpumalangicus , new species

Figs. 1 , 4 , 13 , 29

Type Material. Holotype (male): “ South Africa: Mpumalanga Prov.: VAL 1279E, Vaal River , Stn. VD 1: 261700S- 300315E, marginal vegetation, 19.VII.1960 ( AMG) . Paratypes (5): South Africa: Mpumalanga Province, Headwaters of Vaal River between Breyten & Lake Chrissie, VAL Stn. 1: 743BB, headwater stream, marginal vegetation, 22.VII.1959, (26°17′S, 30°3′15′′E), 22.vii.1959 (1 AMG) ; Vaal River , Stn. VD 1: VAL 1119E, (26°17′S, 30°3′15′′E), 4.v.1960 (2 AMG); VAL 1115 F; Stn. VD 21, VAL 1115F, 5.V.1960, 5.v.1960 (1 AMG); VAL 1212 E ; Mpumalanga Province, Headwaters of Vaal River between Breyten & Lake Chrissie VAL Stn. 1: 1212E, headwater stream, marginal vegetation, 1.VI.1960, 1.vi.1960 (1 AMG) .

Differential diagnosis. Differentiated from other similar members of the O. (A.) continentalis Group by the combination of the dorsum of head and pronotum with very sparse, very fine setae, the pattern of the hydrofuge pubescence on the abdominal ventrites (described below), and by the aedeagus.

Description. Size: holotype (length/width, mm): body 1.10/0.52 (length to elytral apices); head width 0.34; pronotum length 0.28, width at base 0.26, width at hyaline border 0.48; elytra 0.60/0.52. Habitus as illustrated ( Fig. 13 ). Dorsum dark brown to black except hyaline borders of prothorax transparent. Eyes with moderately coarse, convex facets. Frons with deep impressions, borders of impressions rounded. Frons and clypeus very sparsely very finely punctate, interstices shining. Labrum anterior margin arcuate in both sexes.

Pronotum sparsely finely punctate, finely setose, shining; anterior and posterior transverse impressions deep, anterior narrowly separated from shallow transverse impression immediately behind anterior margin of lateral lobe; median longitudinal impression narrow, shallow, connecting anterior and posterior transverse impressions. Pronotum lateral hyaline borders wide, extended from posterior to anterior angles; sides of non-hyaline part with short, sparse, setae immediately above and resting on hyaline border; anterior and posterior hyaline borders narrow.

Elytra wider than non-hyaline part of pronotum, posteriorly rounded, sides arcuate; ten seriate-punctate, punctures large, deep, intervals shining, generally less than width of punctures; each puncture with granule at anterior margin, and decumbent seta that arches over puncture, attaining base of following seta; lateral margin with row of very short, arcuate decumbent setae.

Venter ( Fig. 13 ): Mentum with sparse, moderately large setigerous punctures. Prosternum with midlongitudinal carina. Metaventrite tabella large, kite shaped, with anterior angle extended as carina; width ca. 0.55 width of metaventrite; slightly wider than long (as ca. 110:75, lateral angles slightly rounded (ca. 70 degrees), anterior angle (not including carina) ca. 120 degrees), midline lengths above and below horizontal imaginary line through widest part as 3:5; surface with few random setigerious punctures, setae along posterior margins longer than setae along anterior margins; ventrites 1–3 entirely bearing rather long hydrofuge pubescence; ventrite 4 with reduced hydrofuge pubescence in median ¼; remaining ventrites glabrous, shining, with sparse setae.

Etymology. Named in reference to the known distribution.

Distribution. Currently known only from northeastern South Africa ( Fig. 29 ).

Figures

FIGURE 1. Dorsal habitus of species in the O. (A.) exaratus Group (upper row), and the O. (A.) continentalis Group (remainder).

FIGURE 4. Venter and aedeagi (ventral view, flagellum deleted) of species in O. (A.) continentalis Group and O. (A.) tenuipunctus Group. Not to same scale.

FIGURE 13. O. (A.) mpumalangicus n. sp., holotype habitus and aedeagus.

FIGURES 29–30. Geographical distributions. 29. O. (A.) mpumalangicus n. sp., O. (A.) tenuipunctus Régimbart and O. (A.) solitarius n. sp. 30. O. (A.) libertarius Aguilera et al. and O. (A.) continentalis Orchymont.