Prionocyphon alexanderi, Zwick, 2015

Zwick, Peter, 2015, Three new Marsh Beetles (Col.: Scirtidae) from New Guinea and Java, Linzer biologische Beiträge 47 (2), pp. 1885-1895 : 1886-1889

Prionocyphon alexanderi nov.sp. (Figs 1-9)

H o l o t y p e: Papua New Guinea: Morobe 1000-1300m 13.10.1992 leg. A. Riedel (SMNS).

Habitus. Almost hemispherical, rounded and strongly domed, BL 3.8mm, BL/BW ~1.4, PW corresponds to 87%, HCW to 50% of BW. Punctures on head, pronotum and scutellum very fine and widely spaced, on elytra coarse and very dense, about 1 diameter apart. Head, pronotum, scutellum and antennae orange-red, legs brown, elytra black except caudal fifth orange. All of dorsal side covered with semi-erect whitish hairs (Fig. 1).

Frontoclypeus with straight front edge, no projecting lobes. Eyes large, bulging. Mandibles not studied, maxillary palpus unmodified, last segment of labial palpus inserting at right angle near middle of the transversely extended penultimate segment.

Antenna with large flat scape, the small tubular pedicel inserted on the sharp edge of the scape. Antennomere 3 minute, looking like an annulus at the base of antennomere 4. Antennomeres 4-7 strongly, 8 moderately serrate, 9-11 about tubular (Fig. 1). SAR ending where it meets the eye, not descending in front of the eye. The wide area between eye and edge of oral cavity shallowly concave. End of SGR on lower face of head slightly raised, separated from edge of oral cavity by a small gap ("buttonhole configuration", ZWICK 2013b), not connected to the edge of the oral cavity, nor to other ridges and sutures. Prosternal process and mesoventral groove not studied. Abdomen unmodified, all sternites densely covered with strong socketed hairs, no obvious sensilla except a few along the front edge of S3. Density of pilosity does not differ between sternites.

M a l e. T8 with wide plate, a large forward

directed tongue-shaped lobe between the

straight apodemes. Caudal margin triangu-

lar, setal fringe near middle very long (Fig. Fig. 1: Prionocyphon alexanderi nov.sp.: male, 2). S8 large, a wide U-shaped sclerite, no habitus, dorsal. setae (Fig. 3). Apodemes of T9 closer to-

gether, connected by a sclerite arch. Plate unpigmented, very wide, its sides partly folded mediad. Caudally stand a few very fine setae on either side of a transverse soft field covered with weak microtrichia (Fig. 4). S9 long and slender, with strong concave sclerite strips supporting the caudally widening plate. A tuft of long setae on either side of midline, near caudal margin (Fig. 5).

Tegmen (Fig. 6) with bilobed wide base, the sclerotized area about as long as wide, narrowing caudally and supporting two slender caudally tapering straight parameres. Their soft tips bear some sensory pores, converge, and meet. On the outside the parameres bear numerous thick socketed spines, the mesal edge is smooth. Each spine is parallel over most of its length and apically pointed. In front, spines form an oval patch on the base of the paramere. Near the widest point of the tegmen insert exceptionally strong and long styles whose distinct sclerotized bases curve mediad. Each style is about tubular, with a weak constriction near middle. Apex gently curved outward, outer face with a soft membranous subterminal area. A fringe of long hair-like microtrichia along medial edge takes a hairpin bend at the apex and continues forward for a short distance along a low middle rib.

Penis long and slender, parallel over 2/3 of its length, the slender parameroids converge a little (Fig. 7). A basal lobe of the parameroid extends slightly mediad, over the basal arm of the trigonium. The parameroids are slightly waisted near middle and end in narrow Figs 2-9: Prionocyphon alexanderi nov.sp., male terminalia: (2) T8; (3) S8; (4) T9; (5) S9; (6) tegmen with parameres and styli; (7) penis; (8) trigonium, enlarged; (9) detail of armature on paramere. 2-7 to the same scale. pe, paramere; st, stylus.

flat lobes. Along the medial face the parameroids are covered with flat rounded scales. These are directed backward on the wide basal lobes, are unordered at the narrowest point of the parameroid and point forward on the narrow caudal section. The basal arms of the trigonium converge and meet, forming a parallel sclerite with subterminal triangular expansions and ending in a slender cone (Fig. 8). Ventrally, the distal part of the trigonium bears two irregular rows of strong pointed cones giving it a serrate appearance (Fig. 9). Base of endophallus (Fig. 7) without visible armature. Soft endophallus tissue seems to fill the entire space between the trigonium and the long parameroids.

F e m a l e. Unknown.

N o t e s. There are several colourful Prionocyphon species , P. alexanderi resembles none of them. Details of genitalia differ clearly from all congeners. Prionocyphon alexanderi is more similar to the Holarctic congeners ( NYHOLM 1971, YOSHITOMI 2005, KLAUSNITZER 2009) than to the Taiwanese species ( RUTA 2010, YOSHITOMI 2010). The forward extension of T8 and the bilobed base of tegmen resemble P. serricornis ( MÜLLER, 1821) and the other west-palaearctic species. No Holarctic species seems to have styles, but the "Seitenplättchen" or "Lateralgriffel" which NYHOLM (1971, 1972) described are their homologues; see ZWICK (in prep.) Styles occur in neotropical Prionocyphon species ( KLAUSNITZER 2012b), in P. papuanus nov.sp., and in many Australian Prionocyphon ( WATTS 2010, ZWICK in prep.). However, the complex structure and the strength of the styles of P. alexanderi (Fig. 8) are unique.

E t y m o l o g y. Named for ALEXANDER RIEDEL who collected not only this specimen but many other Scirtidae ( ZWICK 2014) in Irian Jaya.