Helophorus (Ropalohelophorus) brumopluvialis, Bilton, 2023

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 : 258-261

Helophorus (Ropalohelophorus) brumopluvialis sp. nov.

( Figs 1E , 2H–J , 3D , 4B, D, F, H , 5 )

Helophorus aethiops (partim, misidentification): BALFOUR- BROWNE (1954: 105).

Type locality. South Africa, Northern Cape Province,Bokkeveld Plateau, Avontuur Reserve, pools in drying temporary stream, 31°17′38.92″S 19°01′12.03″E, 795 m.

Type material. HOLOTYPE: J, labelled: “ 6/x/2015 South Africa NC // Avontuur Reserve – pools in drying // temporary stream 795m 31 17 38.92S // 19 01 12.03 E D T Bilton leg.” ( AMG) with red holotype label . PARATYPES: 2 JJ 1 ♀, same data as Holotype ( CBP); 10 JJ 7 ♀♀, “ 27/ ix/2010 SouthAfrica WC // Hopefield pools beside // Berg River on dirt road N of // Bergrivier D.T. Bilton leg.” ( AMG, CBP, ISAM, MNHN, NMPC, NMW); 1 J, “ 27/ix/2010 South Africa WC // Hopefield pools beside // Berg River on dirt road N of // Bergrivier D.T.Bilton leg.” “DNA voucher // IBE-DV275” ( CBP); 1♀, “ 27/ix/2010 South Africa WC // Hopefield pools beside // Berg River on dirt road N of // Bergrivier D.T. Bilton leg.” “DNA voucher // IBE-DV276” ( CBP); 2JJ 1♀, “ Sept.2002 South Africa WC // Temporary pond along R315 road // ca. 10 km E of Darling // D.T. Bilton leg.” ( CBP);2JJ 1♀, “ 18/ix/2010 South Africa NC // Temporary pools on R27 road ca. 2 km E.of //Vanrhynspas – pools on sandy soils // D.T.Bilton leg.” ( CBP); 2 JJ, “ 17/ix/2014 South Africa NC // Kamiesberg- seepage pools // beside road 2 km SE of // Leliefontein D.T. Bilton leg.” ( BMNH); 1 ♀, “ 19/ix/2009 South Africa WC // Temp. pool beside R324 road 12 km S of // Barrydale below Tradouw Pass // D.T. Bilton leg.” ( BMNH); 2 JJ 1 ♀, 4 exx., “Stn. No. // 326” [326 Hw.] “S.AFRICA // Kalabaskraal // ca. 350ft. 27.vii.1954 // J. Balfour-Browne” “roadside pond, // much Juncus and Nitella” “J. Balfour-Browne // Brit. Mus. 1954–797” ( BMNH); 1 ♀, “ Para- // type” [circular label with yellow border] “ SOUTH AFRICA: // Milnerton, // Diep River, // 28.ix.1949 // A.D. Harrison.” [date Hw.] “Brit. Mus. // 1951–35” “ Helophorus (s.str.) // aethiops Paratype! // J. Balfour-Browne det. [name and Paratype! Hw.] ( BMNH); 1 ♀, “ Para- // type” [circular label with yellow border]“ SOUTH AFRICA:// Milnerton,// Diep River, // 21.vi.1948 // A.D. Harrison.” [date Hw.] “Brit. Mus. // 1951–35” “ Helophorus (s.str.) // aethiops Paratype!// J. Balfour-Browne det.” [name and Paratype!Hw.] ( BMNH); 1♀, “Stn.No.// 319” [319 Hw.] “S.AFRICA // 6ml. S. of Garies // 2,500ft. 18.vii.1954 // J. Balfour-Browne” “Small muddy // ephemeral pool” “J. Balfour-Browne // Brit. Mus. 1954–797” ( BMNH); 1 exx., “S. AFRICA // near Paarl // 420ft. 10.viii.1954 // J. Balfour-Browne” “Shallow weedy // rivulet” ( BMNH); 1 exx., “Stn. No. // 322” [322 Hw.] “S. AFRICA // Van Rhynsdorp // 400 ft. 19.vii.1954 ” “shallow grassy // farm dam” “J. Balfour-Browne // Brit. Mus.1954–797” ( BMNH); 1 exx., “Stn. No. // 320” [320 Hw.] “S.AFRICA // Bitterfontein // 1,126ft. 18.vii.1954 ” “ephemeral road- // side pool” “J. Balfour-Browne // Brit.Mus. 1954–797” ( BMNH); 1♀, “ Para- // type” [circular label with yellow border] “ SOUTH AFRICA:// Milnerton,// Diep River, // 28.ix.1948 // A.D. Harrison.” [date Hw.] “ Helophorus (s.str.) // aethiops Paratype! // J. Balfour-Browne det.” [name and Paratype! Hw.] “Type // SAM/Ent. // 3610 [3610 Hw.] ( ISAM); 3 JJ 5 ♀♀, “ SOUTH AFRICA, W. Cape, 2 Sept 2003, // leg. C.R. Turner, 33º06’11”S 18º25’22”E, alt: 41m, // Pools in field margins, fine silty with crops protruding, // opposite large grain silos on // R45 east of Hopefield” ( CBP); 156 exx., “ SOUTH AFRICA,W. Cape, 2 Sept 2003, // leg. C.R. Turner, 33º06’11”S 18º25’22”E, alt: 41m, // Pools in field margins, fine silty with crops protruding, // opposite large grain silos on // R45 east of Hopefield” ( CTP), all with red paratype labels.

Description. Male ( Fig. 1E ). Head black, with golden- -green aeneous reflection; strongly shining. Granules weak, central seta-bearing pore always evident, but most granules coalesce with adjacent ones into irregular raised areas; discrete granules more evident laterally on frons and clypeus and immediately in front of Y-groove. Y-groove shallow; floor with dense, coarse, rugose punctures, shining as rest of head; stem evenly diverging anteriorly; lateral branches narrow, straight proximally then weakly arcuate laterally in front of eyes. Clypeus slightly elevated in centre; anterior margin weakly arcuate. Labrum with shining, impunctate, basal portion with anterior margin bisinuous around centre; anterior portion with coarse, rugose punctures, each puncture bearing a short, stout, whitish semi-erect seta; anterior margin arcuate with broad, shallow anteromedian emargination. Antennae 8-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 ( Figs 3D & 4D, F ) predominantly reddish brown, with golden-green aeneous reflections, particularly on internal and middle intervals; anterior and lateral borders paler, yellowish brown; shining over entire dorsal surface. Broadest between middle and anterior margins; very weakly arched in frontal and dorsal views and flattened over internal and middle intervals. Anterior margin almost straight 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 distinctly minutely crenulated to serrate. Internal and middle intervals flat, distinctly granulate, strongly shining; granules flattened and partly coalescent, but evident, all with pore and seta; granules similar on external interval, but more discrete, surface strongly shining and somewhat rugose. Grooves with dense, somewhat rugose, shallow punctures and small raised areas but no clear, discrete, granules. Median groove narrow and parallel-sided, open anteriorly and posteriorly. Submedian and submarginal grooves open anteriorly and posteriorly. Submedian grooves relatively narrow, weakly sinuate. Submarginal grooves straight, broadest anteriorly and broader than submedian. Marginal grooves curved parallel to the side of pronotum, width uniform. All grooves shallow, particularly median and submedian, with sides rounded; transition between grooves and intervals involving relatively small step.

Elytra ( Fig. 1E ) brownish-yellow, with limited diffuse infuscation, coalescing into two discrete patches either side of suture on disc; paler spots visible anterior to dark patches. Shape elongate oval, bluntly rounded at apex. In lateral profile flat over anterior 0.5, then gradually descending to apex. Puncture rows weakly striate, particularly laterally; intervals relatively broad and flat.

Legs yellowish-brown, apex of last tarsal segment and claws slightly infuscated. Legs relatively long; swimming hairs distinct and clearly visible on tarsi.

Venter black, with pronotal hypomeron, antennal pocket and epipleura orange-brown to straw 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 not 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. 2H ) elongate, 0.66 mm in length. Basal piece distinctly longer than parameres; outer margins of parameres sinuous approximately 0.5 from apex and then narrowed more abruptly close to apex; interior margins of parameres abruptly widened subapically, then almost straight. Median lobe with apex rounded; sides diverging posteriorly to base of struts, weakly concave; struts slightly longer than tube.

Female. Externally as males, but typically slightly larger in overall body size.

Measurements. Males: Holotype: BL = 4.00 mm; EL = 2.75; EW = 1.60 mm. Paratype: BL = 3.25–4.20 mm; EL = 2.10–2.85; EW = 1.20–1.65 mm. Females: BL = 4.20–4.65 mm; EL = 2.70–3.25 mm; EW = 1.65–1.90 mm.

Variation. This species exhibits some variation, both within and between populations. In particular, the aeneous reflections on the head and pronotum vary from greenish to purplish to absent, with the background colour of the pronotum varying from pinkish brown to yellowish. In some specimens the granulation of the pronotal intervals is less evident than others, but granules, whilst they are weak and flat, are always evident somewhere on each interval. In some specimens the median groove is widened in the middle. The degree of sculpture visible in the pronotal grooves also varies somewhat, this being correlated with the degree of interval granulation evident, but grooves are always as described above in terms of their relative widths, and their rather weakly-defined margins. The degree of elytral infuscation also varies, from almost absent to being present over much of the disc. In the aedeagus, there is variation size (0.58–0.66 mm – all except smallest male examined (BL = 3.25 mm), from Kalabaskraal, Western Cape Province> 0.60 mm) and in the relative lengths of the basal piece and parameres, these sometimes being subequal and the precise shape of the paramere sides and apices between specimens, this variation being seen within populations when slightly longer series are available ( Figs 2H–J ).

Differential diagnosis. Helophorus brumopluvialis sp. nov. is distinguished by its 8-segmented antennae, rather flat, granulate pronotum with a very narrow submedian groove as well as its relatively large aedeagus, usually with relatively broad tips to the parameres. Some paratypes were originally included in the type series of H. aethiops .

Etymology. From the Latin bruma, winter and pluvial, rain, reflecting the distribution and ecology of the species; adjective.

Distribution and ecology. Apparently restricted to areas of the Western and Northern Cape Provinces of South Africa, in regions experiencing predominantly winter rainfall ( Fig. 5 ). Not so far known to overlap geographically with H. aethiops . Like the latter species, characteristic of shallow, seasonally flooded waters, typically with aquatic grasses, algae and macrophytes, in this case sites that flood following winter rains. Cytochrome oxidase-I DNA sequence divergence between this species and H. aethiops is 5.5–6.0% (I. Ribera, pers. comm.), suggesting that these two species diverged during the Plio-Pleistocene.

Helophorus (Ropalohelophorus)

nyandaruaensis sp. nov.

( Figs 1F , 2K , 3E , 5 )

Helophorus aethiopicus (misidentification): BALFOUR- BROWNE (1954: 105).

Type locality. Kenya,Abadare (Nyandarua) Mountains,south-west face, 2,600 –2,700 m, ca. 0°44′S 36°43′E. Likely in “Prairies découvertes” (open meadows) above a forest hut Alluaud and Jeannel travelled to from Naivasha (see JEANNEL 1950).

Type material. HOLOTYPE: J, labelled: “J” “Afrique or. anglaise // MONTS ABERDERE // VERSANT SUD-OUEST // ALLUAUD & JEANNEL” “LISIÈRE INFÉR. DES FORÊTS // et Prairies découvertes // 2600–2700 m // Févr. 1912 Stn. 57” “ A.d’Orchymont det. // Helophorus s. str.) // aethiopicus Rég. ” [aethiopicus & Rég. Hw.] “ Coll.I.R.Sc.N.R. ” [blue label] and red Holotype label ( RBINS) . PARATYPES: 1 ♀, “ ♀ ” otherwise same data as Holotype ( RBINS); 2 exx., same data as Holotype, but Helophorus also Hw. ( RBINS); 1 J, “J” “Afrique or. anglaise // MONTS ABERDERE // VERSANT SUD-OUEST // ALLUAUD & JEANNEL” “LISIÈRE INFÉR. DES FORÊTS // et Prairies découvertes // 2600–2700 m // Févr. 1912 Stn. 57” “A.d’Orchymont det. // Helophorus s. str.) // aethiopicus Rég. ” [aethiopicus & Rég. Hw.] “Coll. et det. // A. d’Orchymont: // Helophorus // aethiopicus Rég. // R.M.H.N.B. 15.962” [name and describer Hw.] ( RBINS); 1 J, “J” “Afrique or. anglaise // MONTS ABERDERE // VERSANT SUD-OUEST // ALLUAUD & JEANNEL” “LISIÈRE INFÉR. DES FORÊTS // et Prairies découvertes // 2600–2700 m // Févr. 1912 Stn. 57” “A. d’Orchymont det. // Helophorus s. str.) // aethiopicus Rég. ” [aethiopicus & Rég. Hw.] “compare // à aethiopicus” [Hw.] “Coll.I.R.Sc.N.R.” [blue label] ( RBINS);1J, “water // tank” [Hw.] “VAN SOMEREN // NGONG SCARP // MAY, 1943” “IMP. INST. ENT. // COLL. NO. 10643” ( BMNH); 1 ♀, “water // tank” [Hw.] “VAN SOMEREN // NGONG SCARP // MAY, 1943” “IMP.INST. ENT. // COLL. NO. 10643” “ Helophorus (s. str.) // aethiopicus Rég. // J. Balfour-Browne det.” [species name Hw.] ( BMNH); 2 exx., “AFRIQUE ORle ANGLAISE // NAIROBI // (WA-KIKUYU ET MASAI) // CH. ALLUAUD. 2 e SEM. 1903” “ Helophorus // pallidipennis Muls.” [Hw] on same card ( MNHN) all with red paratype labels.

Description. Male ( Fig. 1F ). Head dark brown, with green aeneous reflections; very strongly shining. Granules weak, central seta-bearing pore always evident, often at least partly confluent over central area of frons and clypeus; discrete granules more evident laterally on frons, close to compound eyes and clypeus laterally, in front of Y-groove. Y-groove relatively deep; floor with scattered pits, shining as rest of head; stem evenly diverging anteriorly; lateral branches narrow, relatively straight. Frons either side of Y-groove stem and clypeus slightly elevated in centre; anterior clypeal margin weakly arcuate, almost straight. Labrum with shining basal portion with sparse micropunctures, anterior margin bisinuous around centre; anterior portion with medium punctures, each puncture bearing a short, stout, whitish semi-erect seta; anterior margin arcuate with shallow anteromedian emargination. Antennae 8-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. 3E ) dark brown, with green aeneous reflections; anterior and lateral borders paler brown, anterior pale border narrower than lateral; shining over entire dorsal surface. Broadest between middle and anterior margins; arched in frontal and dorsal views and slightly flattened over internal and middle intervals.Anterior margin weakly bisinuous over central 0.5, then sinuate to broadly rounded front angles; posterior margin broadly bisinuate around centre. Sides straight over posterior 0.3, then weakly arcuate around broadest point to anterior angles. Lateral margins setose and distinctly crenulated to serrate. Internal intervals slightly tumid, granules weak but visible, particularly anteriorly; many reduced to pore and seta centrally and posteriorly; strongly shining. Middle intervals similar to internal, but flatter and granules more evident towards middle. External interval more evidently granulate throughout, particularly on internal side. Grooves shining, with shallow punctures and small raised areas but no clear, discrete, granules. Median groove narrow and rather parallel-sided, open narrowly anteriorly and somewhat wider posteriorly. Submedian and submarginal grooves open anteriorly and posteriorly. Submedian grooves relatively narrow as median, moderately sinuate. Submarginal grooves weakly arcuate, broadest anteriorly and broader than submedian. Marginal grooves curved parallel to the side of pronotum, width uniform. All grooves moderately deep, particularly median and submedian, with margins sloping but distinct; intervals curving down into grooves.

Elytra ( Fig. 1F ) brownish, with limited diffuse paler markings. Shape elongate oval, bluntly rounded at apex. In lateral profile flat over anterior 0.6, then gradually descending to apex. Puncture rows strongly striate, particularly on disc and anterolaterally; intervals slightly raised, rounded.

Legs pale brown, apex of last tarsal segment and claws infuscated. Swimming hairs distinct and clearly visible on tarsi.

Venter black, with pronotal hypomeron, antennal pocket 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 visible from below, but narrower than epipleura. 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. Hind margin of abdominal ventrite 5 with irregular microserrations in centre only.

Aedeagus ( Fig. 2K ) elongate, 0.85 mm in length. Basal piece longer than parameres; outer margins of parameres weakly diverging basally, then weakly converging and strongly converging approximately 0.2 from apex; narrowing to distinctly acuminate tips; interior margins of parameres widening after apex, first 0.5 with different angle to second and with a concave margin. Median lobe with apex bluntly pointed; sides diverging posteriorly to base of struts, distinctly concave; struts approximately 1.25× length of tube.

Female. Externally as males, but slightly larger in overall body size.

Measurements. Holotype: BL = 3.90 mm; EL = 2.65; EW = 1.55 mm. Paratype males: BL = 3.25–3.45 mm; EL = 2.35–2.45 mm; EW = 1.35–1.50 mm. Paratype females: BL = 3.70–4.55 mm; EL = 2.60–3.20 mm; EW = 1.55–1.65 mm.

Variation. Variation evident in size and the degree of paler pigment on elytra. Some paratypes have slightly weaker, or slightly stronger granulation on head and pronotum than in the holotype and a more purplish aeneous sheen. Some variation in size of aedeagus (0.78–0.85 mm), but always very large.

Differential diagnosis. Helophorus nyandaruaensis sp. nov. can be separated from all known African species by its very large aedeagus, with acuminate tips to the parameres. In addition, the species has 8-segmented antennae and is relatively robust, with raised, granulate pronotal intervals.

Etymology. Named after the Nyandarua, the Kikuyu name for the Abadares Range, where the holotype was collected; adjective.

Distribution and ecology. To date, known from only three collections, all in mountains of the East African Rift, close to Nairobi, Kenya ( Fig. 5 ). The holotype and most paratypes were taken by Alluaud and Jeannel in 1912, in the southwestern portion of the Abadare (Nyandarua) Range, in open meadows at 2,600 –2,700 m. An additional male and female (BMNH) were collected in 1943 by Victor Van Someren on the Ngong Scarp, most likely in the present- -day Ngong Hills Forest Reserve, which reaches almost 2,500 m in altitude, southwest of Nairobi. Finally, I have seen two examples in MNHN, collected by Alluaud close to Nairobi in 1903.

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. 4. SouthAfrican Helophorus, SEMs.A, C, E & G – H. aethiops J. Balfour-Browne, 1954, Kokstad, South Africa; B, D, F & H – H. brumopluvialis sp. nov., Hopefield, South Africa.A–B – head detail; C–D – pronota; E–F – pronotal detail, median groove to far left; G–H – left elytral striation close to apex.

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