Laccobius leopardus, Bilton, David T. & Gentili, Elio, 2014

Bilton, David T. & Gentili, Elio, 2014, Laccobius leopardus sp. nov. from the Western Cape of South Africa (Coleoptera: Hydrophilidae), Zootaxa 3835 (3), pp. 397-400 : 397-400

Laccobius leopardus sp. n.

( Fig. 1 )

Type locality. South Africa: Western Cape: Cederberg, Matjies River at Matjiesrivier Reserve ca. 3 km N of Cederberg Oasis, 32° 31’ 10.53”S 19° 21’ 02.63”E, 726 m, D.T. Bilton leg. ( Figure 1 f).

Type material. Holotype (male): “ 22–25/ix/2011 South Africa WC, Cederberg—Matjiesrivier Reserve, Matjies River ca. 3 km N of, Cederberg Oasis D. T. Bilton leg.” (genitalia extracted and mounted in DMHF on same card) and red holotype label ( ISAM). Paratypes (9): 3 ♂, 4 ♀ Same data as holotype ( CDTB, CGV, NMW); 2 ♀ “ 21/ix/2010 South Africa WC, Cederberg—Matjiesrivier Reserve, Matjies River ca. 3 km N of, Cederberg Oasis D. T. Bilton leg ( CDTB).” All with red paratype label.

Description. Size: Holotype: TL = 3.5 mm, MW = 1.65 mm; Paratypes: TL = 3.4–3.7 mm, MW = 1.65–1.75 mm. Colour: Head, including labrum, dark brown with aeneous purplish-green reflections. Distinct pale preocular spots extending from front margins of eyes to frontal angles of clypeus. Pronotum pale straw yellow-yellowish brown, with approximately parallel-sided dark central patch occupying discal 1/3, and broadly reaching front and hind margins. Elytra straw yellow, with diffuse darker patches on disc, and darker rings of pigment around punctures. Venter black, with exception of preocular region of head, pronotal hypomeron and elytral epipleurs and pseudepipleurs, which are straw yellow as upperside, and lateral areas of abdominal ventrites 2–5 which are paler brown. Legs, antennae and palpi straw yellow; trace of infuscation visible on last segment of maxillary palp (see Fig. 1 a–b).

Head: Labrum curved at lateral margins, but broadly truncately rounded at front edge. Upper surface of head, including labrum, shining and distinctly shagreened, with sparse, coarse shallow punctures. Frontoclypeal suture distinct, with coarse punctures posterior to suture and inside each eye, each puncture bearing a long, white decumbent hair-like seta. Eyes oval, moderately large, occupying 1/3 side margin of head. Inter-ocular distance ca. 3.2x diameter of eye.

Pronotum: Transverse; approximately 3x broader than long. Broadly rounded at sides, with acutely rounded front angles, and broadly rounded hind angles. Front margin broadly bisinuate around centre; hind margin weakly curved. Upper surface shagreened, this microsculpture being slightly less impressed than on head, and most evident over central dark patch. With sparse, coarse shallow punctures throughout; these punctures being shallower than those on head. Larger punctures bearing long decumbent hair-like setae, visible particularly towards side margins.

Elytra: Elongate oval, subparallel in basal half and evenly rounded to apex; widest at middle. Elytral punctures rather irregular, some traces of rows on elytral disc. Each puncture bearing a seta. On disc setae of punctures short; not reaching beyond hind margin of puncture. Setae much longer at sides and in apical ½, where many are 5– 6 x puncture diameter in length. Elytral margin with stout bristles on shoulder, and similar, slightly longer, stout bristles in apical half.

Ventral side: Labrum without speculae, front margin broadly curved, and overhanging oral cavity, especially in the centre. Distinct circular apicomedian emargination visible on front margin of labrum, this occupying the downcurved upper surface and front labral edge. Ventral surface of labrum somewhat excavated either side of apicomedian emargination. Apicomedian emargination with a cluster of short, golden setae. Mentum rectangular, shining, lacking microsculpture, and with fine, scattered punctures. Submentum with similar surface properties. Gula and genae microreticulate, dull, with hydrofuge pubescence. Genae rugosely punctate towards lateral margins of head, with distinct field of long, golden, curved, hair-like erect postocular setae. Prosternum roof-like, with a central longitudinal keel. Surface punctate, with hydrofuge pubescence. Mesoventral keel with a distinct hooked anterior tooth. Tooth surrounded by broad lateral expansions, furnished with long white hairs. Keel narrowed and linear between mesocoxae. Metaventrite pubescent, with exception of a glabrous central section. Hairs thinner towards posterior margin. Glabrous central section with distinct longitudinal furrow occupying posterior ¼ of metaventrite. Pubescence overlying distinct micoreticulation; imbricate and isodiametric anteriorly, transverse posteriorly. Abdominal ventrites 1–5 shining, with sparse, coarse punctures, some bearing long golden setae arranged in loose transverse rows. Setae 1/3–3/4 of segment length. Abdominal ventrites broadly excavated laterally. Ventrite 5 with denser punctation; some punctures situated in short transverse furrows. Ventrite 6 dull, pubescent, with transverse microreticulation.

Legs: Moderately long and slender. Segments 2–3 of male protarsi expanded, with smooth sucker plate and modified bristle fields, typical of the genus. Pro and mesotibiae straight; posterior tibiae evenly curved. All tibiae strongly spinose. Procoxae, protrochanters and base of profemora with hydrofuge pubescence. Mesocoxae with hydrofuge pubescence, mesotrochanters and anterobasal portion of mesofemora with scattered long setae. Metacoxae glabrous. Base and posterior margins of metatrochanters and base of metafemora with stout hair-like setae.

Aedeagus: Parameres 2.3x length of phallobase. Paramere apices elongate, finger-like, extending beyond apex of median lobe. Median lobe with broadly rounded apex, and distinct, broad semicircular excavation on ventral face. Minutely dentate internal sac structures visible at base of this excavated area.

Female: Concavity of abdominal ventrites weaker than in males. Foretarsi unmodified. Metatrochanters with much fewer, smaller setae than in male.

Variability: In addition to size differences, specimens vary somewhat in the extent of the dark central patch on the pronotum ( Fig. 1 a–b) and the extent of dark mottling on the elytra, which can be slightly more extensive than seen in the holotype.

Differential diagnosis. L. leopardus sp. nov. is morphologically closest to Laccobius caffer , from which it can be distinguished by its larger size (TL 3.4–3.7 mm vs. 2.5–3.1 mm, see Gentili, 1981), darker dorsal pigmentation, with a broader and typically more parallel-sided central dark patch on the pronotum (see Fig 1 a–c). In addition the anterior labral margin is more evenly curved and less truncate dorsally in examined specimens of L. caffer , and the abdominal ventrites have more well developed paler patches in this species. In L. caffer the margins of abdominal ventrites 2–4, the posterior margin of ventrite 4 and much of abdominal ventrite 5 are pale yellow. The two species also differ significantly in male genitalia ( Fig. 1 d–e).

Distribution. To date only known from the type locality, the sandy gravelly margins of the Matjies River, on the edge of the Cederberg range in the Western Cape Province, South Africa. This locality is situated in a region which is somewhat transitional between the fynbos and succulent karoo biomes (Murcinia & Rutherford, 2006); fynbos occurring at higher altitudes, lower altitude sites such as the type locality being surrounded by succulent karoo.

Etymology. Named in reference to the leopards ( Panthera pardus pardus (Linnaeus)) which frequent the Cederberg Conservancy in which the type locality is situated, and the spotted appearance of the elytra. The name is a noun in apposition.

Ecology. Specimens were puddled by hand from marginal sediment in shallow river backwaters ( Fig. 1 f), which were mostly without appreciable surface flow at the time of sampling, but would clearly be connected to the main river at times of higher flow. They occurred together with the water beetles Hydropeplus montanus Omer-Cooper , Herophydrus inquinatus (Boheman) , Sharphydrus brincki Bilton , Yola frontalis Régimbart , Hydroglyphus infirmus (Boheman) , H. lineolatus (Boheman) , Canthyporus guignoti Omer-Cooper , C. petulans Guignot , Philaccolus lineatoguttatus (Régimbart) , Laccophilus lineatus Aubé , Georyssus spp., Berosus punctulatus Boheman , Laccobius revelieri Perris , L. venustus Gentili , Helochares spp., Crenitis zimmermanni Knisch , Parasthetops nigritus Perkins & J. Balfour-Browne , P. pampinus Perkins , P. rufulus Perkins & J. Balfour-Browne and Prosthetops wolfbergensis Bilton.

Figures

FIGURE 1. Morphology and habitat of Laccobius species. a) L. leopardus sp. nov. holotype dorsal habitus. b) L. leopardus sp. nov. paratype head and pronotum. c) L. caffer dorsal habitus. d) L. leopardus sp. nov. aedeagus ventral and lateral views. e) L. caffer aedeagus ventral and lateral views. f) L. leopardus sp. nov. type locality: South Africa, Western Cape, Cederberg, Matjies River at Matjiesrivier Reserve ca. 3 km N of Cederberg Oasis (photo: D. T. Bilton). Scale bars a – c = 1 mm; d – e = 500 Μm.