Ochthebius (Aulacochthebius) flagellissimus, 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 : 520-521

O. (Aulacochthebius) flagellissimus , new species

Figs. 1 , 4 , 11 , 26

Type Material. Holotype (male): South Africa : Western Cape Province, “S. Afr.: S. W. Cape, Nuweberg, 10 km NE, 34°00′ S, 19°06′ E, shore washing, 13.xi.1973, leg. Endrödy-Younga (#240)” ( TMSA) . Paratypes (111): Same data as holotype (54 TMSA) . South Africa: Northern Cape Province, Temp pools on R27 ca 2 km E of Vanrhynspas—sandy soils, (31°23′.96′′S, 19°1′21.72′′E), 27.ix.2011, leg. D. T. Bilton (6 DTBC) ; Western Cape Province, Paarl Vlei on Wemmershoek road; FRW 115P, (34°4′S, 19°0′E), 14.ix.1955, leg. unknown (1 AMG) ; S. W. Cape, Nuweberg , 10km NE, (34°3′S, 19°6′E), 13.xi.1973, leg. Endrödy-Younga (#239) (50 TMSA) . Other material: Same data as holotype (non-types in alcohol, 880 TMSA); S. W . Cape, Nuweberg , 10km NE, (34°3′S, 19°6′E), 13.xi.1973, leg. Endrödy-Younga (#239) (non-types in alcohol, 125 TMSA) .

Differential diagnosis. Differentiated from other similar members of the O. (A.) continentalis Group by the combination of the abdominal venter with shining large suboval glabrous area bearing sparse, rather long setae, remainder of ventrites with hydrofuge pubescence, and by the aedeagus.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.10/0.50; head width 0.33; pronotum length 0.27, width at base 0.23, width at hyaline border 0.45; elytra 0.64/0.50. Habitus as illustrated ( Fig. 11 ). 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 moderately densely finely punctate, interstices shining. Labrum anterior margin arcuate in both sexes.

Pronotum moderately densely, 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, inconspicuous 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 moderately large, deep, intervals shining, ca. same width as punctures; each puncture with distinct 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. 11 ): Mentum with sparse, moderately large setigerous punctures. Prosternum with very low midlongitudinal carina. Metaventrite tabella large, diamond shaped, width ca. 0.6 width of metaventrite, slightly longer than wide, lateral angles sharp (ca. 68 degrees), anterior angle cariniform (anterior angle ca. 112 degrees), surface with few random setigerious punctures, mostly in anterior 0.5, setae along posterior margins longer than setae along anterior margins. Abdominal venter with shining large suboval glabrous area bearing sparse, rather long setae, remainder of ventrites with hydrofuge pubescence.

Etymology. Named in reference to the incredibly long aedeagal flagellum, which is nearly twice as long as the beetle’s body.

Distribution. Currently known from southern and southwestern South Africa ( Fig. 26 ).

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 11. O. (A.) flagellisimus n. sp., holotype habitus and aedeagus.

FIGURES 24–26. Geographical distributions. 24. O. (A.) continentalis Orchymont. 25. O. (A.) scutatus n. sp. 26. O. (A.) persetosus n. sp. and O. (A.) flagellissimus n. sp.