Mescirtes javanicus, Zwick, 2015

Zwick, Peter, 2015, Three new Marsh Beetles (Col.: Scirtidae) from New Guinea and Java, Linzer biologische Beiträge 47 (2), pp. 1885-1895 : 1891-1894

Mescirtes javanicus nov.sp. ( Figs 13-19 )

H o l o t y p e: Java : Gn. Gede-Pangrango NP ca 5km SW Cipanas 14-16.Oct. 1991, C. Reid, D. Subasli \ under leaves, trees & bushes rainfor. By ravine ca. 1400-1550m (Left elytron and hind legs missing; ANIC) .

Habitus. Stout and strongly domed, almost hemispherical. BL 2.2mm, BL/BW ~1.3. Head wide ( Figs 13, 14 ), HCW corresponds to ~53% of BW. Head, pronotum, lower face and appendages light orange-brown, elytra chocolate brown, the caudal fourth abruptly light orange-brown. Colour of scutellum orange-brownish. Entire surface with fine semi-erect silvery pilosity. Punctures on elytra very fine and dense, still finer on pronotum, almost imperceptible on head, except on the projecting clypeal lobes where a few large shallow punctures occur. Clypeal fore margin straight in middle above labrum (lb) but curving forward and outward laterally, forming rounded lobes that are smaller than the neighbouring flat scape ( Fig. 13 , sc).

Antenna distinctly serrate ( Fig. 15 ). Scape disc-like, with sharp outer edge, lower face flat, upper convex. Pedicel spherical, inserted on the edge of scape. Antennomere 3 minute, no more than a tranverse ring at the base of antennomere 4 which has a very narrow base and is slightly concave on the outside, widening quickly on inner side, distal af, antennal foramen; cl, clypeal lobe; f1, front femur; gs, branch from gular suture; lb, labrum; lm, rm, left and right mandible; lp, labial palpus; m, mentum; mp, maxillary palpus; pp, prosternal process; SAR, supraantennal ridge; sc, scape; SGR, subgenal ridge; tr, trochanter.

half about parallel, half as wide as long, truncate at apex, inner corner blunt. Distal antennomeres successively less wide, the terminal one about rectangular and 3x as long as wide.

Left mandible with sharp slender tip, a small denticle near midlength, the wide molar area smooth, flat ( Fig. 13 ). Right mandible concealed. Maxillary palpus with simple conical end segment, terminal segment of labial palpus standing at right angle near midlength of 2nd segment ( Fig. 14 ).

Front and middle legs unmodified, hind legs missing.

Lower face. There is a deep, wide subantennal groove ( Fig. 13 , arrow) with smooth impunctate floor between the eye and the ventrally projecting mouthparts. The antennal foramen is in vertical position, at the top end of the groove ( Fig. 14 ). The groove is visible only from below, the large scape hides it in front. The sharp edge of the groove is formed by the SAR which continues downward in front of the eye ( Fig. 14 ) and forms a shallow sharp pre-ocular crest. On the lower face of the head the SAR curves mediad towards the edge of the oral cavity. The SGR runs on the underside of the head over most of its length, far from the eye. Its front end curves mediad towards the oral cavity and ends closely behind the SAR. The ends of the two ridges include a triangular area between them ( Fig. 14 ).

Prosternal process an elongate plate with rounded front margin, widening backwards, caudally rounded ( Fig. 14 ). Mesoventral groove a wide U-shaped depression. Mesoventral process wide, not longer than the groove in front of it, caudally distinctly incised.

Abdominal sternites unmodified, S3 without mesal longitudinal ridge. Fine pilosity present only in middle, areas above femora bare. S4 and S5 completely covered with setae, a row of setiform sensilla only along front edge. Density of pilosity increases slightly on S6 and further on S7, both lack sensilla. S7 caudally with indistinct shallow notch.

Ma l e. Tergite 8 completely membranous and bare, short and transverse. Only the short caudally inward curved apodemes are pigmented ( Fig. 16 ). Sternite 8 is a U-shaped very weak sclerite, hard to see (not illustrated). Apodemes of T9 longer than of T8, straight, pigmented, the bare soft plate is transparent, no defined shape ( Fig. 17 ). At 400x, faint traces of longitudinally oriented microtrichia appear. Of S9 only the transverse distal portion and some vague shades of parallel sclerite stripes are visible. Caudal edge of plate with a few short setae ( Fig. 18 ).

Tegmen an elongate-oval plate, caudal third much narrower than rest and divided into two short lobes, the parameres ( Fig. 19 ; one paramere damaged). Penis slender, front end widest, gradually narrowing caudally, caudal sixth almost conical, end divided into two short sharp-tipped lobes. Between them rises a slender flagellum-like process whose end rests between the parameres. By transparency it is seen to be formed by convergent and eventually merging sclerite strips on the dorsal side of the penis tube ( Fig. 19 ).

F e m a l e. Unknown.

Notes. The genitalia of the present species are very similar to M. gagatinus MOTSCHULSKY (from India or Ceylon; see RUTA 2009: figs 46-51) and M. laosensis YOSHITOMI et SATÔ. RUTA (2009) wondered about possible synonymy between these two uniformly dark species. M. javanicus differs clearly by its bicolorous body. In colouration, the new species resembles M. rutilicollis KLAUSNITZER, 2012a but the reddish area at the end of the elytra is several times larger, and the genitalia are clearly different.

The previously undescribed deep subantennal groove is an additional character separating Mescirtes from Prionocyphon . Mescirtes gagatinus apparently has a similar clypeus but RUTA (2009) mentioned no antennal groove. Prionocyphon papuanus and the Australian species of Prionocyphon with prominent clypeal lobes (ZWICK, in prep.) have no such groove, the wide space between eye and mouthparts is nearly flat.

E t y m o l o g y. Named after the island of origin, an adjective.

Figures

Figs 13-19: Mescirtes javanicus, nov.sp., male: (13) head, dorsal view, right scape removed to expose subantennal groove (arrow); (14) ventro-caudal view of head and part of prothorax; (15) base of right antenna, ventral view; (16) T8; 17, T9; 18, S9; 19, penis and tegmen. 13, 14 not to scale, diagrammatic; 16-18 to the same scale.