Ancyronyx minutulus Freitag & Jäch, 2007

Freitag, Hendrik & Jäch, Manfred A., 2007, The genus Ancyronyx Erichson, 1847 (Coleoptera, Elmidae) in Palawan and Busuanga, (Philippines) with descriptions of six new species, Zootaxa 1590, pp. 37-59 : 53-55

Ancyronyx minutulus Freitag & Jäch sp. n.

( Figs. 9 , 15 a–f)

Type locality. Balsahan River, Iwahig District, Puerto Princesa City, Palawan, Philippines.

Type material. Holotype ď ( NMW): “ PHILIPPINEN.: Palawan 9 km W P. Princesa Iwahig,Balsahan riv. lg. Zettel, 24.3.1994 (48)”, dissected (terminal parts of abdomen, aedeagus and one leg glued separately), major parts of abdomen and one leg missing.

Diagnosis. 1.0 mm long (CL), 0.38 mm broad (EW), 2.6 times as broad as wide (CL/EW). Body form elongate, moderately convex dorsally.

Colouration ( Fig. 9 ) predominantly dark brown (labrum, maxillary palpi, clypeus, frons, pronotum, scutellum, parts of elytra); elytra with two pairs of elongately oval yellowish patches; ventral side distinctly paler brown than dark dorsal parts; legs predominantly yellowish, but base and apex of femur, base and tip of tibia, and apex of terminal tarsal segment brownish; antennae yellowish, distally slightly darkened.

Head 0.24 mm broad (HW); ID 0.15 mm; labrum slightly pubescent, appearing glabrous; frons and clypeus finely punctate, moderately densely pubescent; frontoclypeal suture hardly discernible. Eyes moderately protruding. Antennae 11-segmented, slender, approximately as long as HW. Gula microreticulate; gular sutures narrowly separated mesally, inconspicuous.

Pronotum 0.30 mm long (PL), 0.32 mm broad (MW), ca. 0.9 times as long as wide (PL/MW), widest at ca. posterior 0.4, anteriorly attenuate; anterior margin nearly straight; margin between pronotum and hypomeron conspiciuous; anterior transverse groove distinct; posterolateral oblique grooves inconspicuous; pronotal surface microreticulate and pubescent, a small part close to scutellum almost glabrous. Prosternum distinctly punctate, interstices granulose.

Elytra elongately oval, 0.74 mm long (EL), ca. 1.8 times as long as wide (EL/EW), with ca. eight longitudinal, moderately regular, slightly impressed rows of punctures (five strial rows between suture and shoulder); punctures moderately large and moderately deeply impressed, including those at yellowish patches; interstices and intervals convex, glabrous; lateral elytral gutter narrow; elytra apically conjointly rounded. Meso- and metaventrite distinctly punctate; interstices glabrous; metaventral longitudinal groove distinct and moderately long. Hind wings absent.

Legs slightly shorter than body; setae rather small and inconspicuous; claws well developed, strongly curved, base of each claw with projection carrying one very small and inconspicuous tooth.

Sternite IX ( Fig. 15 c) ca. 275 m long; apical margin almost straight, very slightly emarginate, without setae; paraprocts not reaching apical margin.

Aedeagus ( Fig. 15 a, b) ca. 325 m long. Median lobe rather long and slender (ca. 65 m broad), subapically evenly acuminate, slightly curved ventrad (lateral view), with numerous distinct microtube-like structures mainly ending lateroapically; ventral sac plicate, with moderately sclerotized, conspicuous fibula; ejaculatory duct distinctly speckled from level of parameral base to parameral apex; corona weekly developed. Phallobase asymmetrical, basally slightly curved ventrad (lateral view), with conspicuous, strongly sclerotized margin and short medial longitudinal ridge; basolateral (penile) apophyses rather long. Parameres elongately subtriangular (lateral view), reaching ca. basal 0.6 of aedeagus; basal margin sinuately emarginate (lateral view), not contiguous ventrally.

Secondary sexual characters. Male sternite VIII incomplete ( Fig. 15 d), weekly sclerotized; median strut short, apically rounded. Male tergite VIII ( Fig. 15 e) slightly broader than long, condyles inconspicuous, basal half with microstrial pattern. Male ventrite 5 ( Fig. 15 f) subtrapezoidal, apically slightly microreticulate, medially rather glabrous, basal half with microstrial pattern.

Female unknown.

Differential diagnosis. In this species the elytral colour patches are more elongate than in the other species described herein. Additionally, A. minutulus can easily be distinguished by its small size in combination with its entirely dark pronotum.

Distribution (Fig. 17). Only known from the type locality.

Etymology. Minutulus (lat.) very small. Named in reference to the fact that this species is the smallest representative of the genus so far described.

Figures

FIGURE 15. Ancyronyx minutulus sp. n., holotype: a, b) aedeagus in ventral and lateral view; c) male sternite IX (strioles omitted); d) male sternite VIII (strioles omitted); e) male tergite VIII (setae and structures of left half omitted); f) male ventrite 5 (setae and strioles of left half omitted).

FIGURES 7 – 10. Habitus of 7) Ancyronyx minerva sp. n., paratype Ψ; 8) A. minerva sp. n., paratype Ψ, winged, partly completed; 9) A. minutulus sp. n., holotype ♂, partly completed; 10) A. helgeschneideri sp. n., paratype Ψ.