Helophorus (Ropalohelophorus) cooperi Orchymont, 1947

Bilton, David T., 2023, Out of the Palaearctic: the Helophorus water beetles of the Afrotropical Region (Coleoptera: Helophoridae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 63 (2), pp. 249-264 : 255-258

Helophorus (Ropalohelophorus) cooperi Orchymont, 1947 , stat. nov.

( Figs 1D , 2G , 3C , 5 )

Helophorus aethiopicus cooperi Orchymont, 1947: 722

Type locality. Ethiopia, Oromiya Region, Wourambouchi, close to Djem-Djem Forest, ca. 60 km W of Addis-Abbaba, approximately 9°03′N 38°09′E, ca. 2,750 m. Exact details imprecise. Wouramboulchi is a frequent locality on historical specimens from the region and was close to Djem-Djem Forest.

Type material. HOLOTYPE: J, labelled:“J” “ Abyssinia // Wouramboulchi // 9,000ft. // 2-7.x.1926. // J. Omer-Cooper. ” “TYPE” [pink label] “ A. d’Orchymont det. // Helophorus (s.str.) aethio // picus cooperi m.” [name Hw.] ( BMNH). PARATYPES: 1 ♀, “ ♀ ” otherwise same data as Holotype ( BMNH); 1♀, “ ♀ ” “ Abyssinia // Wouramboulchi // 9,000ft. // 2-7.x.1926. // J. Omer-Cooper. ” “ A. d’Orchymont det. // Helophorus (s.str.) aethio // picus cooperi m.” [name Hw.] “ Para- // type” [pink label) ( RBINS).

Redescription. Male ( Fig. 1D ). Head dark brown to black, with green aeneous reflection; shining. Granules evident over entire frons and clypeus, but partly or fully coalescent with adjacent granules in places. Y-groove relatively shallow; floor shining, with dense, shallow, coarse, rugose punctures; stem weakly diverging anteriorly; lateral branches narrow, particularly over apical 0.5, straight. Clypeus strongly elevated in centre; anterior margin weakly arcuate. Labrum with shining, impunctate, basal portion with anterior margin produced and rounded at centre; anterior portion with coarse, rugose punctures, each puncture bearing a short, stout, whitish semi-erect seta; anterior margin arcuate with shallow anteromedian emargination. Antennae 9-segmented, yellowish brown, with cupule and club segments darker. Maxillary palpi yellow, apex of terminal segment infuscated; moderately elongate, terminal segment longest, curved and clearly asymmetrical.

Pronotum ( Fig. 3C ) pale reddish brown, with pale green aeneous reflections weak and restricted to sublateral groove; anterior and lateral borders paler, but contrast with remainder of pronotum indistinct; shining over entire dorsal surface. Broadest between middle and anterior margins; weakly arched in frontal and dorsal views and somewhat flattened over internal intervals, particularly anteriorly. Anterior margin slightly concave over central 0.5, then sinuate to broadly rounded front angles; posterior margin broadly bisinuate around centre. Sides straight over posterior 0.4, then weakly arcuate around broadest point to anterior angles. Lateral margins setose and crenulated to serrate. Internal and middle intervals slightly arched, strongly shining; granules reduced to pore and seta. External interval strongly shining with weak granules evident, particularly anteriorly. Grooves smooth and shining, with sparse punctures and wrinkles, particularly in sublateral and lateral. Median groove narrowed anteriorly, more so posteriorly, open at both ends more widely so anteriorly. Submedian and submarginal grooves broadly open anteriorly and posteriorly. Submedian grooves relatively narrow, weakly sinuate. Submarginal grooves almost straight, much broader than submedian. Marginal grooves curved parallel to the side of pronotum, width uniform.All grooves relatively deep, with intervals curving down towards their margins, which are well-defined but somewhat sloping rather than vertical.

Elytra ( Fig. 1D ) brown, with diffuse paler markings, particularly posteriorly. Shape elongate oval, sides rounded to bluntly rounded apex. In lateral profile flat over anterior 0.5, then gradually descending to apex. Puncture rows weakly striate, more so laterally; intervals slightly arched anteriorly and flatter posteriorly.

Legs yellowish-brown, apex of last tarsal segment and claws infuscated. Swimming hairs distinct and clearly visible.

Venter black, with pronotal hypomeron, antennal pocket and pseudepipleura and epipleura brown to yellow. Mentum shining, centre without microreticulation, with sparse, medium punctures; lateral marginal areas with weak isodiametric microreticulation centrally; margins with fine yellow setae, denser towards posterolateral angles. Submentum shining, without microreticulation; anterior half with sparse, shallow, coarse punctures and fine, hair-like vestiture. Gula and genae rugose, with dense hydrofuge vestiture. Gular sutures well marked as pits anteriorly. Vestiture only absent around margin of compound eyes and their posterolateral corners. Prosternum dull, rugose, with dense hydrofuge vestiture and sparse, long, erect setae approximately 2× length of vestiture. Pronotal hypomeron dull, with dense hydrofuge vestiture. Pronotal epipleura shining, glabrous, with sparse shallow punctures. Anterior antennal pocket well developed, with long, dense setae internally and long, curved setae at posterolateral margins. Elytral epipleura dull, glabrous, narrowing posteriorly at level of metaventrite and continuing until posterior margin of ventrite. Elytral flanks very narrowly visible from below. Ventral surface of mesothorax, metathorax and abdomen dull, with dense hydrofuge vestiture and longer, erect setae; longer setae concentrated on centre of metaventrite and abdominal ventrites 2–5; setae on ventrites arising from longitudinal tubercles, which sometimes appear as shining patches. Hind margin of abdominal ventrite 5 weakly crenulate.

Aedeagus ( Fig. 2G ) elongate, 0.65 mm in length. Parameres slightly shorter than basal piece; outer margins of parameres sinuate approximately 0.5 from apex; interior margins of parameres initially sloping, then rather straight, apices acuminated. Median lobe narrow, with weakly pointed apex; sides diverging posteriorly to base of struts, weakly concave; struts as long as tube.

Female. Externally as males.

Measurements. Males: Holotype: BL = 3.45 mm; EL = 2.30; EW = 1.40 mm. Females: BL = 3.50–4.00 mm; EL = 2.50–2.65 mm; EW = 1.45–1.65 mm.

Variation. Limited, other than in size – note that only three specimens of this taxon are available, however.

Differential diagnosis. Helophorus cooperi has a very distinctive pronotal sculpture, with smooth internal and middle intervals, 9-segmented antennae and a characteristic aedeagus.

Distribution and ecology. Known only from the type locality, Wourambouchi, close to Djem-Djem Forest in the Oromiya Region, ca. 60 km W of Addis-Ababa at approximately 2,750 m ( Fig. 5 ). Helophorus aethiopicus is recorded both north and south of this locality and the precise distribution of, and possible ecological differences between, the two species remain unknown.

Figures

Fig. 1. Afrotropical Helophorus, habitus. A – H. aethiopicus Régimbart, 1907, lectotype; B – H. aethiops J. Balfour-Browne, 1954, holotype; C – H. aethiops J. Balfour-Browne, 1954, Kokstad, South Africa; D – H. cooperi Orchymont, 1947, holotype; E – H. brumopluvialis sp. nov., holotype; F – H. nyandaruaensis sp. nov., holotype; G – H. simiensis sp. nov., holotype. Scale bar = 1 mm.

Fig. 2. Afrotropical Helophorus, aedeagi. A – H. aethiopicus Régimbart, 1907, lectotype; B – H. aethiopicus, paralectotype; C – H. aethiops J. Balfour-Browne, 1954, holotype; D–F – H. aethiops J. Balfour-Browne, 1954, Kokstad, South Africa; G – H. cooperi Orchymont, 1947, holotype; H – H. brumopluvialis sp. nov., holotype; I–J – H. brumopluvialis sp. nov., Hopefield, South Africa; K – H. nyandaruaensis sp. nov., holotype; L – H. simiensis sp. nov., holotype. Scale bar = 100 μm.

Fig. 3. Afrotropical Helophorus, pronota.A – H. aethiopicus Régimbart, 1907, lectotype; B – H.aethiops J. Balfour-Browne, 1954, holotype; C – H. cooperi Orchymont, 1947, holotype; D – H. brumopluvialis sp. nov., holotype; E – H. nyandaruaensis sp. nov., holotype; F – H. simiensis sp. nov., holotype.

Fig. 5. Afrotropical Helophorus, known distributions.Map by https:// mapswire.com.