Ancyronyx jaechi, Freitag, Hendrik, 2012

Freitag, Hendrik, 2012, Ancyronyx jaechi sp. n. from Sri Lanka, the first record of the genus Ancyronyx Erichson, 1847 (Insecta: Coleoptera: Elmidae) from the Indian Subcontinent, and a world checklist of species, Zootaxa 3382, pp. 59-65 : 60-63

Ancyronyx jaechi , sp. n.

Type locality. Kuda Oya River, Ambapussa, Warakapola City, Kegalle District, Sabaragamuwa Province, Sri Lanka.

Type material. Holotype 3 ( NMW): “ SRI LANKA: Warakapola, Ambapussa, Kuda Oya River; small mountain river; secondary vegetation/ village; riffle, submerged wood, moderately polluted; c. 80m asl, c.7°13ʹN 80°11ʹE 0 4.1.1992 leg. Freitag (1a)”, terminal parts of abdomen incl. aedeagus glued separately. Paratypes: 2 Ƥ, 13 ( NMW, ZSM [FR027], SMTD): same data as holotype.

Description. Body form elongate, slightly convex dorsally; body 2.1–2.6 mm long (CL + exposed portion of head); CL: 1.91–2.21 mm; EW: 0.81–0.95 mm; CL/EW: 2.3–2.4.

Colouration as in Fig. 1 : ventral side, coxae, femora, distal half of tibiae, posterior portion of pronotum, frons between antennae, antennae (except tips), maxillary palpi, elytral apices and a distinct elytral pattern of obliquely crossing lines yellowish; claws, antennal tips, and ventrites darker yellowish to pale brown; remaining parts dark brown.

HW 0.48–0.57 mm; ID 0.25–0.28 mm; labrum and clypeus micropunctate, moderately densely covered with small trichoid setae; frons microreticulate and punctate; frontoclypeal suture straight to slightly convex, slightly impressed. Eyes protruding. Antennae with 11 antennomeres, slender, slightly longer than width of head. Gula indistinctly microreticulate, posterior portions laterally rugose and reticulate, without conspicuous pubescence; gular sutures absent.

Pronotum 0.51–0.58 mm long (PL), 0.66–0.76 mm wide (MW), distinctly wider than long (PL/MW), widest at about anterior 0.4 (level of procoxae), slightly narrower than elytra, with distinct but rather shallow transverse groove dividing pronotum into a pale, distinctly broader posterior portion and a dark, shorter and narrower anterior portion; anterior and posterior of transverse groove slightly vaulted; posterolateral oblique grooves very inconspicuous; lateral margin distinctly arcuate; anterior margin convex; pronotal surface entirely microreticulate and with irregularly arranged small shallow punctures; lateral pronotal carina absent; hypomeron inconspicuously reticulate. Prosternum micropunctate; prosternal process broadly subrectangular, wider than long, very slightly convex, lateral and posterior margin distinctly elevated from a parallel-sided shallow groove; lateral grooves connected to a small round impression; posterior margin slightly convex.

Metascutellum subcordiform, medially impressed, at least median portion glabrous. Elytra elongate, 1.40–1.63 mm long (EL), ca. 1.7 times as long as wide (EL/EW), slightly tapering toward apices from ca. 0.1–0.7, posteriorly roundly convergent to apices; elytral apices separately rounded; with ten longitudinal, moderately impressed rows of punctures (counted at level of metacoxae); six strial rows between suture and humerus, inner two merge at anterior 0.2; punctures large and deeply impressed; interstices and intervals convex, granulose to microreticulate; lateral elytral gutter narrow; humeri prominent. Mesoventrite short, divided by longitudinal impression into two subpentagonal plates, with few inconspicuous punctures, almost glabrous. Metaventrite large, medial longitudinal suture somewhat carinately elevated in posterior half in both sexes; longitudinal medial impression widest at anterior and posterior margins, narrow and shallow at about anterior 0.25; disc with scattered inconspicuous setose tubercles, glabrous in-between; tubercles larger and denser toward lateral declivity; anepisternum 3 microreticulate with additional scattered punctures. Hind wings present; venation not examined.

Legs ca. 1.35 times as long as body; coxae very large, lateral portion visible in dorsal view; pro- and mesocoxae subglobular; metacoxae only slightly protruding laterally; femora and tibiae with micro-setiferous tubercles; tibiae distally with few trichoid setae; claws strongly bent, base of each with three teeth, distal one largest, basal one small and hardly perceptible.

Ventrites 1–4 with small, moderately densely arranged punctures, surface glabrous between punctures; ventrite 5 ( Figs 2 E, F) moderately densely covered with short adpressed setae emerging from flat tubercles; lateral projection inconspicuous.

Sternite IX ( Fig. 2 D) with anterior median strut rather short, apical margin deeply emarginate; paraprocts short, not reaching apical margin.

Aedeagus ( Figs 2 A, B) in general shape and proportions similar to that of A. hjarnei Jäch, 2003 (comp. Jäch, 2003: Figs. 2 –5), but distinctly larger, 450 µm long. Median lobe comparably long and moderately wide (ca. 90 µm), only slightly tapering, almost parallel-sided up to apical 0.1; apex distinctly curved ventrad, with numerous distinct pore-like structures on dorsal side; ventral sac weakly sclerotized, plicate; fibula moderately sclerotized, rather inconspicuous; corona elongate, conspicuous in transillumination ( Fig. 2 B). Phallobase slightly asymmetrical, basal margin obliquely truncate, rather weakly sclerotized; basolateral apophyses indistinct. Parameres appearing slightly unequal in size (right one larger), elongately subtriangular, slender, with few (ca. six) moderately long apical setae (partly broken off in the figured specimen); basal margin emarginate (lateral view, Fig. 2 A), reaching about basal 0.75 of aedeagus, presumably not contiguous ventrally.

Ovipositor ( Fig. 2 C) ca. 360 µm long. Stylus slender, moderately bent outwards, with various sensilla. Coxite short and stout, somewhat bent; distal portion with several rather short and broad, peg-like spines, most densely set subapically at lateral margins; inner margin pubescent; basal portion with rather slender and pointed spines, basally with striolate patches. Valvifer approximately as long as coxite, apical margin with few rather long spines; fibula slightly curved inwards caudally.

Secondary sexual characters: sternite VIII in female distinctly longer, slightly more sclerotized than in male and with median strut apically widened (short, evenly tapering and apically rounded in male), posterior portion pubescent (not conspicuous in males). Tergite VIII in female (mutilated during dissection) short, distinctly wider than long, with few moderately long setae, condyles inconspicuous or damaged during dissection. Tergite VIII in male slightly longer than in female, but still distinctly wider than long, laterally with conspicuous long setae. Ventrite 5 in female ( Fig. 2 E) subtriangular, in male ( Fig. 2 F) similar in general shape, but slightly smaller and rather suboval.

Larva: unknown.

Differential diagnosis. Ancyronyx jaechi sp. n. superficially resembles other species of the A. variegatus species group (sensu Freitag & Jäch, 2007) in size and general habitus. In general, colouration of legs, pronotum, and elytra, A. jaechi sp. n. resembles the rather widespread A. procerus Jäch, 1994 , while its cross-like elytral colour pattern also resembles A. schillhammeri Jäch, 1994 . However, it can easily be distinguished from all other species of the genus by the combination of the dorsal colouration and its genital characters. The shape and distribution of the spines of the ovipositor’s coxite resemble somewhat those of A. procerus (comp. Jäch, 1994: Fig. 15), which, however, is distinctly larger. The male genitalia are most similar to those of A. hjarnei Jäch, 2003 . However, the aedeagus of the latter is distinctly smaller and has a medially produced phallobase in ventral view (rather truncate in A. jaechi , sp. n.).

Distribution. Only known from the type locality.

Etymology. The new species is named for Dr. Manfred Alexander Jäch, world-famous specialist of aquatic beetles and curator at the World Water Beetle Research & Collection Centre, Natural History Museum Vienna, Austria, to honour his excellent contributions to the knowledge of the genus Ancyronyx and the aquatic Coleoptera of Sri Lanka.

Figures

FIGURE 1. Habitus of Ancyronyx jaechi, sp. n. (paratype female)

FIGURE 2. Ancyronyx jaechi, sp. n., paratype male & paratype female: A) aedeagus in lateral view; B) aedeagus in ventral view; C) ovipositor in ventral view (right half); D) male sternite IX (one paraproct omitted); E) female ventrite 5; F) male ventrite 5. Scales: 0.1 mm.