Ochthebius (Aulacochthebius) strangulatus, 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 : 516-517

O. (Aulacochthebius) strangulatus Régimbart , new status

Figs. 1 , 3 , 7 , 27, 28

Ochthebius strangulatus Régimbart 1906: 274

O. (Aulacochthebius) exaratus Mulsant ; Orchymont 1948. Misidentification.

Type locality: Kenya (Maji ya Chumvi [“ Maji-Chumvi ”]; Samburu) .

Material examined (51): Benin: Dep. Mono, Come, Dohi (village), (6°23′7.4′′N, 1°56′14.5′′E), 2.ii.2006, leg. Goergen, Komarek & Houngua (7) (1 NMW) ; Dep. Mono, Lakossa, Doukonta (village), ca. 40 m a.s.l., (6°40′21.3′′N, 1°41′33.5′′E), 2.ii.2006, leg. Goergen, Komarek & Houngua (9) (1 NMW) ; Dep. Zou, Zogbodome, Lokoli (forest), Hianzoun riv., (7°3′N, 2°15′E), 3.ii.2006, leg. Goergen, Komarek & Houngua (14) (2 NMW) . Burkina Faso: Obire , UV light trap, 15.ii.1995, leg. J. F. Cornell (7 NMW) . Gambia: Outside Abuko Nature Reserve at Water Works , 18.30–21.00, 4.xi.1977, leg. Cederholm — Danielsson — Hammarstedt — Hedquist — Samuelsson (1 LUM) ; River Tanji , 3 km SW Brufut, 19.00–21.00, 28.ii.1977, leg. Cederholm — Danielsson — Hammarstedt — Hedquist — Samuelsson (2 LUM) . Ghana: Northern region, Nabogo , 40 km N of Tamale, 21.i.1970, leg. S. Endrödy-Younga (Nr. 410) (6 HNHM) ; Nyankpala , 10.ii.1970, leg. S. Endrödy-Younga (3 TMSA) . Kenya: Kilifi Co., Kaloleni , road C107, KEN 16-32, 3.8155S 39.6229E, 174m, 29.I.2016, Pools in dry streambed, in open landscape, 29.i.2016, leg. J. Bergsten & O. Bistrom (1 KNM) ; Killfi Co., Tributary to Galana river , elev. 6 m (3°8′15.72′′S, 40°5′53.16′′E), 28.i.2016, leg. J. Bergsten & O. Bistrom (KEN 16-30) (8 KNM) . Mali: Mopti, Niger river , (14°30′N, 4°12′W), 21.ii.2000, leg. Komarek & Mayer (21-1) (2 NMW) ; San, Bani River , (13°18′N, 4°54′W), 22.ii.2000, leg. Komarek & Mayer (22-1) (2 NMW) . Nigeria: Argungu , NW State, 22.xii.1974, leg. J. T. Medler (6 NMNH) ; Oyo Provence, Ogbomosho , (12-13)- II-1949, B. Malkin, (8°8′N, 4°15′E) (9 NHMUK) . Senegal: 3 km SSW Toubakouta , 10 km S Ziguinchor, 19.00–22.00, 4.iii.1977, leg. Cederholm — Danielsson — Hammarstedt — Hedquist — Samuelsson (2 LUM) . Uganda: Queen Elizabeth National Park , (0°8′14′′S, 30°2′28′′E), 2.v.1968, leg. P. J. Spangler (1 NMNH) .

Discussion. Orchymont (1929) suggested that O. (A.) strangulatus was a junior synonym of O. (A.) exaratus , under the section on O. (A.) exaratus in a “Tableau des Espèces” including the phrase [“(? strangulatus Reg. )”]. Later, Orchymont (1948) effectively removed the “?” by expressing the view that there is a transition in dorsal characters from O. (A.) exaratus to O. (A.) strangulatus , and cited a male from Nairobi as being “un exemplaire formant passage à strangulatus .” The catalogue of Hansen (1998) included strangulatus as one of the synonyms of O. (A.) exaratus .

As is discussed in the O. (A.) exaratus section on types, the aedeagi of O. (A.) exaratus and (A.) strangulatus clearly differ, and represent two species. There are also external differences, mostly pertaining to the distributions and lengths of setae.

Differential Diagnosis. Refer to the differential diagnosis of O. (A.) copiosus n. sp.

Redescription. Size: specimen from Kenya (length/width, mm): body (length to elytral apices) 1.12/0.54; head width 0.32; pronotum 0.23/0.40; elytra 0.70/0.54. Habitus as illustrated ( Fig. 7 ). Dorsum dark brown except hyaline borders of prothorax transparent. Eyes with moderately coarse, convex facets. Frons with deep impressions, borders of impressions rounded, smooth. Clypeus with very few, very shallow finely setigerous punctures. Labrum apicomedially produced in male, rounded in female.

Pronotal reliefs very smooth, with very sparse and very short indistinct setae; anterior and posterior transverse impressions deep, anterior narrowly separated from transverse impression immediately behind anterior margin of lateral lobe; median longitudinal impression deep, extended from anterior to posterior impression. Pronotum lateral hyaline borders moderately wide, present only in angulation behind lateral lobes; sides of lateral lobes with short setae that extend outward from cuticle in dry specimens; anterior hyaline border moderately wide; posterior hyaline border narrow.

Elytra smooth, ten seriate-punctate, punctures small; on disc each puncture with very fine very short almost imperceptible seta, which lies flat on cuticle, setae more conspicuous and longer laterally and at elytral apices; minute granule at anterior margin of each puncture, more obvious on disc; setae on lateral margins only moderately dense and only moderately long, in dry specimens extending outward from cuticle on in anterior ¼ to 1/3, otherwise mostly lying flat on cuticle.

Venter ( Fig. 7 ): Mentum with sparse, small setigerous punctures. Prosternum with very low midlongitudinal subcarina. Metaventrite tabella large, angulate anteriorly and laterally, length slightly less than width (ratio ca. 7:9); ratio of length above and below horizontal imaginary line through greatest width ca. 3:4; lateral angles slightly rounded; surface with very few, very fine punctures; tabella bordered by moderately long to long setae. Abdominal venter: first two ventrites and antero-lateral margin of third with hydrofuge pubescence, remainder of ventrites shining, with very sparse setae.

Distribution. Currently known from Kenya, Nigeria, and Uganda ( Figs. 26 , 27 ).

Figures

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

FIGURE 3. Aedeagi (ventral view, flagellum deleted) and venter of species in the O. (A.) exaratus Group.

FIGURE 7. O. (A.) strangulatus Régimbart, habitus and aedeagus of specimen from Kenya.

FIGURES 27–28. Geographical distributions. 27. O. (A.) species in Kenya and Uganda. 28. O. (A.) strangulatus Régimbart, O. (A.) tenuipunctus Régimbart and O. (A.) nigeriensis n. sp.

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.