Hydraena (Hydraenopsis) matyoti Jaech & Delgado

Jaech, Manfred A. & Delgado, Juan A., 2016, Hydraena Kugelann, 1794 (Coleoptera, Hydraenidae) from the Seychelles, Indian Ocean, with description of a new species, ZooKeys 623, pp. 75-88 : 77-83

Taxon classification Animalia Coleoptera Hydraenidae

Hydraena (Hydraenopsis) matyoti Jaech & Delgado sp. n. Figs 2, 12-14, 15-19

Hydraena (Hydraenopsis) mahensis : Jäch & Madl 2009: 19 (partim), 29.

Type locality.

Small puddle on Sans Souci Hiking Trail, northern Mahé, Seychelles.

Type material.

Holotype ♂ (NMW), glued on pinned card, genitalia extracted and glued on same card. Label data: "SEYCHELLES: Mahé Sans Souci, XI. 1994, leg.E.Heiss". Paratypes: 1 ♀ (NMW): same label data as holotype; 1 ♂ (NMW): "SEYCHELLES: Mahé Morne Seychellois NP Casse Dent, trail 25.03.2011 leg. M.Madl"; 2 ♀♀ (NMW): "SEYCHELLEN, Mahé 1996 Morne Seychellois NP Congo Rouge 600-800m 25. V. leg. Schödl (12c)"; 1 ♀ (NMW): "Seychelles, Silhouette, Jardin Marron [field name], 400m, 12. 4. 2007, leg. Wewalka (12)".

Description.

Habitus as in Fig. 2. Body length (without abdomen): 1.56-1.70 mm. Dorsum reddish brown, lateral parts of frons (near eyes) more or less black; maxillary palpi yellowish, apical tip paled.

Labrum deeply excised anteriorly; anterior angles rounded. Middle of clypeus sparsely punctate, usually glabrous, lateral parts usually micropunctate and mat. Fronto-clypeal suture straight or feebly arcuate, slightly impressed. Frons moderately densely (middle) or more densely and sometimes even rugosely (laterally) punctate, interstices shining; interocular grooves shallow. Eyes large, protruding, more than 30 facets visible in dorsal view.

Pronotum distinctly wider than long, widest near middle; anterior margin concave; anterior angles rounded; lateral margin very slightly concave in anterior and posterior half; lateral rim denticulate; surface moderately densely to densely punctate, but disc sometimes only sparsely punctate; anterior discal foveae obsolete, posterior discal foveae hardly noticeable.

Elytra elongately oval; with about nine rows of punctures between suture and shoulder; punctures small, but rather deeply impressed, usually arranged in regular, usually not impressed lines; intervals sometimes convex, glabrous; explanate margin of elytra comparably wide, abruptly attenuate subapically, slightly to distinctly serrate posteriorly. Elytral apices usually separately rounded.

Foretibia and metatibia sexually dimorphic.

Mesoventral process parallel-sided, apically truncate, width sexually dimorphic. Metaventrite moderately deeply impressed between glabrous metaventral plaques, the latter reduced to very thin glabrous elevated short, widely separated streaks.

Male terminal sternite and spiculum (Fig. 15): Sternite not firmly connected with spiculum, subtrapezoidal, approximately as wide as long, slightly asymmetrical; base with very small lateral projections.

Aedeagus (Figs 12-14): Total length: 400 µm. Main piece elongate, in apical half divided into a ventral and a dorsal branch, ventral branch with characteristic claw-like apex; single dorsal seta inserted on dorsal branch near base of distal lobe; phallobase strongly asymmetrical, closed proximally. Distal lobe inserted on dorsal branch of main piece; moderately large, amorphic, partly distinctly hyaline. Right paramere long and slender, with rows of subapical setae; articulately connected with main piece. Left paramere absent.The aedeagus can be distinguished from the aedeagi of Hydraena borbonica Fairmaire, 1898 (from La Réunion) and Hydraena ofella Balfour-Browne, 1958 (from the Comoros) by the wider and less regular shape of the ventral branch of the main piece.

Gonocoxite (Fig. 16): Subtrapezoidal, strongly transverse; basal part without setae, distal part strongly setose; basal apophyses small; inner plate slightly projecting.

Female tergite X (Fig. 17): Subsemicircular, transverse; disc sparsely covered with trichoid setae; subapical setae vermiform; apical margin without excision.

Spermatheca (Figs 18-19): Proximal portion crescentic; distal portion elongately cup-shaped.

Secondary sexual characters: Foretibia and metatibia slightly curved in male. Male mesoventral process more slender; in male more or less as wide as mesotibia, in female slightly wider than mesotibia.

Habitat.

On Mahé this species was collected in a small puddle on a forest trail (leg. E. Heiss), and in small mountain streams at more than 600 m a.s.l. (leg. M. Madl and S. Schödl) - the single specimen collected by M. Madl was found on a small piece of wood lying in a very small stream (Fig. 21). A single female was collected on Silhouette, Jardin Marron, near a hiking trail, ca. 400 m a.s.l., approx. 4°29.16'S 55°14.16'E, on a hygropetric rockface (leg. G. Wewalka).

Distribution.

Endemic to the Inner Seychelles. So far known only from Mahé and Silhouette.

Etymology.

This species is named for Pat Matyot, a Seychellois naturalist with a special interest in entomology. Pat Matyot is employed by the Seychelles Broadcasting Corporation and has produced many television features on the country’s fauna and flora. He has served on the boards and science committees of a number of conservation organisations in Seychelles and is at present a board member of the Island Conservation Society (ICS) and the Silhouette Foundation. The epithet is a noun in the genitive case.