Laccobius (Glyptolaccobius) pluvialis, Gentili, 2006

Gentili, Elio, 2006, Revisional notes on the genus Laccobius. I. Subgenus Glyptolaccobius (Coleoptera: Hydrophilidae), Acta Entomologica Musei Nationalis Pragae 46, pp. 57-76 : 68-70

Laccobius (Glyptolaccobius) pluvialis sp. nov.

( Figs. 1-3 , 27-29 )

Type locality. India NE, Meghalaya, SW of Cherrapunjee, 900 m a.s.l.

Type material. HOLOTYPE: J, 1.9 × 1.1 mm ( NHMW): ‘NE INDIA, MEGHALAYA, / SW of CHERRAPUNJEE, / 25°13-14′ N, 91°40′E, / 5.-24.V. 2005, 900 m, / P. Pacholatko leg. ’. PARATYPES: 180 spec. (NHMW, MSNV, CFHG), same data as holotype.

Description. Total length 1.7-2.2 mm, total width 1. 0-1.2 mm. Body ( Fig. 1 ) oval, convex, its outline not interrupted between pronotum and elytra; elytra not explanate.

Head. Labrum of males without specula; trapezoidal in dorsal view, with straight anterior and posterior margins and faintly oblique sides. Clypeus strongly convex, not deflexed towards margins, black and shining, without distinct ‘systematic punctures’. Eyes oblique, slightly reniform in lateral view, straight anteriorly and emarginate posteriorly, weakly convex, not protruding, separated by a little more than 2.5 times the width of one eye. Maxillary palpi less than 0.5x as long as head wide; palpomere 2 not swollen, as wide as palpomere 3; apical segment nearly 0.3 times as long as whole palpus, asymmetrical, outer margin nearly straight, inner margin rounded, with truncate apex. Mentum ca 1.5 times as wide as long, surface punctate, almost flat. Eight antennomeres ( Fig. 3 ); scape (antennomere 1) longer than antennomeres 2-4 together; pedicel (antennomere 2) cone shaped; two intermediate antennomeres (3-4) very short; cupule (antennomere 5) slightly asymmetrical, crescent-shaped in ventral view, nearly flat in dorsal view; segment 3 of club nearly twice as long as segment 1, the latter more stout but nearly as long as segment 2 of club.

Thorax. Pronotum smooth and shining, without distinct ‘systematic punctures’, only with sparse and faint punctures; disc black, yellow lateral margins wider posteriorly. Prosternum well developed, disc slightly bulging; median carina fine and in part obsolete. Mesoventrite only reaching anterior margin of mesothorax in a single point, rather flat except for median carina, the latter more raised anteriorly and forming a small acute tooth anterior of mesocoxae. Metaventrite with middle portion rather weakly raised and slightly projecting anteriorly between mesocoxae, covered with hydrofuge pubescence except for posteromedian glabrous area on raised middle portion. Anepisternum 3 ca 3.5 times as long as wide, subparallel. Elytra with a hardly visible parasutural stria on posterior third, without trace of serial punctures; dark on disc, near suture and along anterior margin, chestnut-yellow near posterior and lateral margins, with yellow and darker colours mixed in contact zone; lateral margins not serrate nor denticulate; epipleura oblique, pseudepipleura nearly vertical, separated by distinct ridge consisting of small arcs; their anterior widened portion ending before metacoxae. Hind wing ( Fig. 2 ) with r-m crossvein rising from distal half of the pigmented area at anterior wing margin; wedge cell only slightly more than half as long as basal cell; jugal lobe distinctly demarcated from remainder of wing by sharp and rather deep excision at posterior wing margin.

Legs. Fore coxae pubescent, almost contiguous; middle coxae separated by median carina of mesoventrite; trochanters pubescent, especially middle ones; tips of hind trochanters free, not abutted to hind femora. Femora with distinct tibial grooves distally on inner face; base of fore femora pubescent, middle and posterior femora nearly glabrous, middle femora with a subbasal patch of dense stiff setae in both sexes. Tibiae relatively short and stout, progressively wider towards apices, spiny, with three longitudinal series of short spines and two large apical thorns; without swimming hairs; hind tibiae curved inward. Fore tarsomeres 2 and 3 expanded in males; middle and hind tarsi with fine and sparse swimming hairs on dorsal face; hind tarsomere 1 much shorter than tarsomere 2. Claws of moderate size, robust, weakly curved.

Abdomen. Six visible ventrites, ventrites 1-5 rather shiny and sparsely pubescent, ventrite 6 more dull, densely pubescent and somewhat retractable; ventrite 1 not carinate; posterior margin of ventrite 5 subtruncate.

Male genitalia.Aedeagus as in Figs. 27-29 ; phallobase nearly 0.5 times as long as parameres, median lobe with swelling before apex.

Differential diagnosis. Laccobius pluvialis sp. nov. is extremely close to L. jaechi and L. eliogentilii in body shape and colour, including the pubescent surface with irregular punctation and the parasutural furrow recognizable barely in the apical fifth. The elytra lack basal spots and parasutural stripes but are widely chestnut-yellowish near the lateral margins and apex. The phallobase is distinctly shorter than in L. jaechi ; finally, the subapical swelling of the median lobe differentiates this species from L. eliogentilii .

Etymology. This species is named in reference to the extreme rainfall records reported from the area close to the type locality.

Distribution. India (Meghalaya). So far known only from the type locality.

Figures

Figs. 1-4. 1-3 – Laccobius pluvialis sp. nov., paratype. 1 – habitus, ventral view; 2 – right wing; 3 – right antenna. 4 – L. incisus Gentili, 1989, paratype, habitus, dorsal view.

Figs. 23-29. 23-26 – Laccobius munus Gentili, 1995, holotype. 23 – aedeagus, dorsal view; 24– ditto, lateral view; 25 – ditto, ventral view; 26 – genital segment. 27-29 – L. pluvialis sp. nov., holotype. 27 – aedeagus, ventral view; 28 – ditto, lateral view; 29 – genital segment.