Orectochilus orbisonorum Miller, Mazzoldi and Wheeler

Miller, Kelly B., Mazzoldi, Paolo & Wheeler, Quentin D., 2008, An unusual new species of Gyrinidae (Coleoptera), Orectochilus orbisonorum n. sp., from India, Zootaxa 1712, pp. 65-68 : 66-68

Orectochilus orbisonorum Miller, Mazzoldi and Wheeler , new species

( Figs 1–6 )

Diagnosis. This is the only species of Indian Orectochilus that is dorsally nearly entirely black ( Fig. 1 ) with a largely white venter ( Fig. 2 ). Other characters in diagnostic combination include: 1) the margin of the setose region on the elytron is evenly curved and slightly convex medially (Figs 1,3); 2) the apical 1/5 of the elytron is setose (Figs 1,3); 3) the margin of the setose region on the pronotum is concave and anteriorly extends medially to a level slightly past the middle of the compound eye (Figs 1,3); and 4) the labrum is broad (width/ length = 3.9) ( Fig. 1 ). The male genitalia are also diagnostic (Figs 6,7). The median lobe in ventral aspect is elongate and slender with the apex abruptly narrowed ( Fig. 6 ). In lateral aspect it is slightly curved ventrad apically ( Fig. 7 ).

This species keys to Vazirani’s (1984) Group 2 of Orectochilus (Patrus) . Although this group may be largely artificial, it is easily diagnosed from all other species in that group by the white venter. This new species is also similar in several respects to three species from southern India, O. discifer (Walker, 1859) , O. punctulatus Régimbart, 1886 and O. fraternus Régimbart, 1886 (the last not included in Vazirani’s (1984) work since it is known from Sri Lanka). From these three species our new one can be distinguished by the shape of the aedeagus ( Fig. 6 ), the more rounded shape of the pronoto-elytral glabrous area at the posterior apex ( Fig 1 ) and the microsculpture which in O. orbisonorum is formed by small isodiametric cells, whereas it is almost obsolete in O. discifer and indistinct and formed by narrow, transversely elongated meshes in both O. punctulatus and O. fraternus .

Description. Measurements: TL = 4.98–5.38 mm, GW = 2.03–2.22 mm, GH = 1.62–1.83, TL/GW = 2.42–2.45.

Coloration: Dorsal surfaces black, lateral margins of pronotum and elytra white ( Fig. 1 ). Head appendages testaceous except labial palpi white ( Figs 1–3 ). Legs white except protarsi, apex of profemur, margins of protibia and lateral surface of metaxocae testaceous. Ventral surfaces white and testaceous to black ( Fig. 2 ). Prosternum white medially, laterally testaceous; pronotal epipleuron white; propleuron testaceous. Mesepisternum testaceous, other mesosterna white. Metasternum white. Two basal visible abdominal sterna medially white, laterally testaceous; visible abdominal sterna III–VI white, sometimes with lateral margins testaceous; apical visible sternum rufotestaceous. Epipleuron white.

Sculpture and structure: Surface of head, pronotum and elytra with distinct microreticulation consisting of small, isodiametric cells. Labrum broad, width/length = 3.9, anterior margin broadly curved ( Fig. 1 ). Pronotum with lateral pubescence extending medially to middle of eye along anterior margin, posteriorly abruptly constricted, medial margin evenly concave (Figs 2,3). Elytron with lateral pubescence relatively broad anteriorly, medial margin slightly convex medially (Figs 2,3); pubescence confluent along suture in posterior 1/5 of elytra (Figs 2,3). Posterolateral elytral angle obtuse, rounded ( Figs 1–3 ).

Male genitalia: Median lobe in ventral aspect slender, elongate, medially slightly constricted, subapically abruptly narrowed, apex narrow and apically narrowly rounded ( Fig. 6 ); median lobe in lateral aspect slender, apically slightly but distinctly bent ventrad, apex narrowly rounded ( Fig. 7 ). Lateral lobe moderately broad, apex broadly rounded, with dense series of elongate, fine setae along apical margins ( Fig. 6 ).

Female: Gonocoxosternite narrow, elongate, apically narrowly rounded, anterior apodeme slender ( Fig. 5 ); vagina elongate, broad ( Fig. 5 ); bursa short, broad ( Fig. 5 ); spermathecal duct arising apicoventrally on bursa, broad, not strongly differentiated from tubular, contorted spermatheca ( Fig. 5 ); fertilization duct narrowed to broad, flattened sac which opens at base of common oviduct ( Fig. 5 ); with elongate, slender accessory gland inserting dorsally on bursa ( Fig. 5 ).

Sexual dimorphism: Male protarsus large and broadly expanded compared with female ( Fig. 4 , TiL = 34.3–36.1mm, TaL = 22.6–24.4mm, TaW = 9.4–9.9mm, TiL/TaL = 1.5–1.6, TaL/TaW = 2.4–2.5).

Etymology. This species is named in honor of recording artist, songwriter and rock and roll pioneer, Roy Orbison and his wife Barbara

Distribution. This species is known only from central areas of the Western Ghats in southwestern India.

Material examined. Holotype, male in MSBC labeled, “ INDIA: Karnataka, Agumbe Ghats 13º29.852’N 75º04.221’E 09 October 2004 coll. K.B. Miller/ HOLOTYPE Orectochilus orbisonorum Miller, Mazzoldi and Wheeler, 2007 [red label with black line border].” Four paratypes (2 males, 2 females) with same label data as holotype. Two paratypes (females) labeled, “ INDIA: Karnataka 20km E Udupi, forest 04 October 2004 coll.

K.B. Miller.” One paratype (female) labeled, INDIA: Maharashtra, Mulshi 18º26.665'N 75º25.654'E 28 September 2004 coll. K.B. Miller.”

Discussion. The ventrally white condition in this species is atypical for Orectochilus , but is a relatively common character state in the primarily Africotropical Orectogyrus and numerous species of Aulonogyrus Motschulsky, 1853 . A white venter is also present in very few Enhydrini Régimbart, such as the genus Porrorhynchus Gemminger and Harold, 1871 , and the putatively plesiomorphic Spanglerogyrus albiventris Folkerts, 1979 the only member of the subfamily Spanglerogyrinae Folkerts. The white condition in these species, and O. orbisonorum , is due not to white cuticle, but rather to clear cuticle through which the white internal tissues are easily visible.

Specimens were found primarily while collecting at mercury vapor lamps at night in the Western Ghats regions of southwestern India. However, specimens were also collected rarely from the small torrential streams in this area where other Orectochilus can be found abundantly in sheltered areas behind rocks.

Figures

FIGURES 1 – 7. Orectochilus orbisonorum n. sp. 1) dorsal habitus showing color pattern, labrum extended anteriorly, 2) ventral habitus showing color pattern, 3) left lateral habitus, 4) male left protibia and protarsus, anterior aspect, 5) female genitalia (AG = accessory gland; BC = bursa copulatrix; CO = common oviduct; FD = fertilization duct; GC = gonocoxa; SD = spermathecal duct; SP = spermatheca; VA = vagina), 6) male median lobe and left lateral lobe, dorsal aspect, 7) male median lobe, right lateral aspect. scale bar = 1 mm for 1 – 3 only.