Helophorus (Ropalohelophorus) aethiopicus Régimbart, 1907

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 : 250-253

Helophorus (Ropalohelophorus) aethiopicus Régimbart, 1907

( Figs 1A , 2A–B , 3A , 5 )

Helophorus aethiopicus Régimbart, 1907: 127 .

Type locality. Ethiopia, Oromiya Region, Karsa (Kersa), approximately 7°45′S 37°00′E,> 1,740 m. Exact details imprecise. Karsa (or Kersa) is a woreda (district) in the Oromiya Region of southern Ethiopia, whose altitude ranges from 1,740 –2,660 m.

Type material. LECTOTYPE: J, labelled:“J” “ LECTO- // TYPE” [circular label with purple margin] “MUSEUM PARIS // ÉTHIOPIE MÉRID // KARSSA // Maurice de Rothschild // 1905” “ Helophorus // aethiopicus Rég. typus” [Hw.] “ LECTOTYPE 1974 // H. aethiopicus Rég. // R. B. Angus det.” [LECTOTYPE, 74 and name and describer Hw.] “1974 // H. mervensis Sem. // R. B. Angus det.” [74 and name and describer Hw.] ( MNHN) . PARALECTOTYPES: 1J, “ PARA- // LECTO- // TYPE” [circular label with blue margin] “MUSEUM PARIS // ÉTHIOPIE MÉRID // KARSSA // Maurice de Rothschild // 1905” “ Helophorus // aethiopicus Rég. // n. sp. // Type - 1906” [Hw.] “ PARALECTOTYPE Sept1974 // H. aethiopicus Rég. // R. B. Angus det.” [LECTOTYPE, Sept, 74 and name and describer Hw.] “1974 // H. mervensis Sem. // R. B. Angus det.” [74 and name and describer Hw.] ( MNHN); 1 ♀, “ ♀ ” “ PARA- // LECTO- // TYPE” [circular label with blue margin] “MUSEUM PARIS // ÉTHIOPIE MÉRID // KARSSA // Maurice de Rothschild // 1905” “TYPE” [red label] “ PARALECTOTYPE Sept1974 // H. aethiopicus Rég. // R. B. Angus det.” [LECTOTYPE, Sept, 74 and name and describer Hw.] ( MNHN); 1 ♀, “ PARA- // LECTO- // TYPE” [circular label with blue margin] “TYPE” [red printing] “MUSEUM PARIS // ÉTHIOPIE MÉRID // KARSSA // Maurice de Rothschild // 1905” “ Helophorus // aethiopicus // Rég. n. sp. // Type // 1906” [Hw.] “ PARALECTOTYPE Sept1974 // H. aethiopicus Rég. // R. B. Angus det.” [LECTOTYPE, Sept, 74 and name and describer Hw.] “1974 // H. mervensis Sem. // R. B. Angus det.” [74 and name and describer Hw.] ( MNHN).

Other material examined. 1J, “ ETHIOPIA: Oromia // Bale Mountains NP // 5 km NW Dinsho // small lake” “ 07°07′15.62′′N / 39°43′10.52′′E // 3057 m a.s.l. // 22.II.2014 // leg. M.A. Jäch (12)ˮ ( NMW); 2 ♀♀, “ ETHIOPIA: Oromia // Bale Mountains NP // 5 km NW Dinsho // stream” “ 07°07′24.47′′N / 39°44′26.31′′E // 3044 m a.s.l. // 20.II.2014 // leg. M.A. Jäch (12)ˮ ( NMW); 1 J, “J” “ Ethiopie: Goba // R. de Meulenaere // 1934-1935” “R. Mus. Hist. Nat. // Belge. I.G 10.738” “A. d’Orchymont det. // Helophorus s. str. // aethiopicus Rég. ” [name and describer Hw.] ( RBINS); 9 exx., “ Ethiopie: Goba // R. de Meulenaere // 1934-1935” “R. Mus. Hist. Nat. // Belge. I.G 10.738” ( RBINS); 2 JJ 1 ♀ “ Ethiopie: Goba // R. de Meulenaere // 1934-1935” “ Ethiopie: Goba // R. de Meulenaere // 1934-1935” “R. Mus. Hist. Nat. // Belge. I.G 10.738” “Coll. I.R.Sc.N.B.” ( RBINS) [blue label].

Redescription. Male ( Fig. 1A ). Head dark brown to black, with strong green to purplish aeneous reflection; strongly shining. Granules mostly absent, reduced to a central seta-bearing pore over central areas of frons and clypeus; more evident inside compound eyes, laterally on clypeus and immediately in front of Y-groove. Y-groove relatively deep; floor of stem with dense, coarse, rugose punctures, punctures in lateral branches smaller, shining as rest of head; stem evenly diverging anteriorly; lateral branches narrow, particularly over apical 0.5, straight proximally then weakly arcuate laterally in front of eyes. Clypeus strongly elevated in centre; anterior margin almost straight. Labrum with shining, impunctate, basal portion with anterior margin acuminate 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. 3A ), reddish brown, with strong green to purple aeneous reflections, particularly on internal intervals; anterior border narrowly and lateral borders more widely paler, yellowish brown; 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 weakly crenulated to serrate. Internal and middle intervals slightly arched, strongly shining; most granules reduced to pore and seta; granules more evident on anterior portion of both intervals, particularly middle. External interval, surface strongly shining with evident granules anteriorly. Grooves smooth and shining, median and submedian with almost coalescent, shallow punctures, giving a somewhat rugose appearance; submarginal and marginal with irregular small bumps. Median groove narrowed anteriorly, less so posteriorly, open at both ends more widely so posteriorly. Submedian and submarginal grooves broadly open anteriorly and posteriorly. Submedian grooves relatively broad, distinctly sinuate. Submarginal grooves weakly arcuate, 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. 1A ) 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 moderately striate, particularly on disc and laterally; intervals arched.

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 0.5 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 ( Figs 2A–B ), elongate, 0.45 mm in length. Parameres longer than basal piece; outer margins of parameres straight almost to apex; interior margins of parameres rather straight, apices pointed. Median lobe narrow, with weakly pointed apex; sides diverging slightly posteriorly to base of struts, weakly concave; struts distinctly shorter than tube.

Female. Externally as male.

Measurements. Lectotype: BL = 2.90 mm; EL = 2.00; EW = 1.25 mm. Males: BL = 2.75–2.80 mm; EL = 1.15– 2.00 mm; EW = 1.20–1.25 mm. Females: BL = 2.60–3.50 mm; EL = 1.80–2.50 mm; EW = 1.20–1.50 mm.

Variation. Some variation in colour of elytra, some of the paralectotypes and additional specimens being somewhat paler than the lectotype illustrated. Punctation of pronotal grooves also varies somewhat, being more pronounced in some specimens, including paralectotypes, than in the lectotype.

Differential diagnosis. This species can be distinguished by its 9-segemented antennae, relatively small size, weak pronotal granulation and the structure of the aedeagus.

Distribution and ecology. Only known from Ethiopia ( Fig. 5 ), from three collections from two separate areas of the southern highlands; the Oromiya Region in the southwest (type locality) and the Bale Mountains across the Ethiopian Rift Valley to the East. Potentially widespread in these southern high mountain districts, all localities being over 2,500 m.

Comment. Robert Angus had considered that this species could be a synonym of H. mervensis Semenow, 1900 known from Armenia, through Arabia to Iran, Central Asia and Kashmir, something reflected by labels on part of the material examined (see above). Despite this, the two were never formally synonymised ( ANGUS 1971, 1986). My assessment is that, whilst these taxa are similar, they are not conspecific. The aedeagi of these species are very close indeed, but the beetles themselves differ. Based on my examination of specimens from Iran, Kashmir and Central Asia (Golodnya Steppe, Uzbekistan and Shymkent, Kazakhstan) H. mervensis is comparatively more elongate and paler that H. aethiopicus (ground colour of pronotum pale brown with aeneous reflections; elytra pale brown to yellow). In addition, the pronotal granulation of H. mervensis is typically more reduced than in all the H. aethiopicus I have seen, internal intervals in particular lacking any evident granules in most specimens. The pronotal grooves also appear shallower in H. mervensis , and the elytral striae less deep apically, with flatter intervals than in H. aethiopicus , although, as stated by ANGUS (1986) this character varies. Given the similarities, particularly in aedeagi, it may be that H. mervensis and H. aethiopicus share a relatively recent common ancestor, one sublineage of which colonised Ethiopia. Clearly this hypothesis should be tested with DNA sequence data when practicable. AN- GUS (1986) lists four species described by David Sharp as synonyms of H. mervensis and notes the variability of the species as currently defined. Whether it represents a single, widespread, Palaearctic species, or a complex, seems impossible to resolve without genetic data.

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.