Tectocyphon, Zwick, Peter, 2015

Zwick, Peter, 2015, Australian Marsh Beetles (Coleoptera: Scirtidae). 8. The new genera Cygnocyphon, Eximiocyphon, Paracyphon, Leptocyphon, Tectocyphon, and additions to Contacyphon de Gozis, Nanocyphon Zwick and Eurycyphon Watts, Zootaxa 3981 (4), pp. 451-490 : 459-460

Tectocyphon , n. gen.

Type species: Tectocyphon microphallus , n. sp.

Diagnosis. The relatively flat body is oval, the side edges of the elytra and pronotum form a single continuous curve, with no gap between them. Head concealed under the brim-like front margin of the pronotum. The pronotum is small but strongly transverse, a smooth screen with rounded front margin, no distinct angles. The elytral epipleura is wide and flat, not grooved.

Male. The penis base is medially unsclerotized, the lateral penis sclerites are divided, or connected by a cartilage-like strip. The trigonium is shorter than the parameroids, varying in size and shape between species. The spade-shaped tegmen supporting the divergent arms of the parameres rests between the lateral sclerites of the pala. Each paramere has near the base a movable appendage armed with teeth.

Female (known only of T. victoriae ). Sternites 4–6 each with an area with microscopic pores and fine pilosity. Segment 8 and ovipositor unmodified, the prehensor includes a flat sclerite strongly toothed along the sides.

Description. Habitus ( Figs. 21–26 ). Oval, the highest point of the relatively flat body is behind the middle of the elytra. Head transverse and short, concealed under front margin of pronotum. Labrum small, a transverse rectangle with rounded front corners. Mandibles stout, sharply pointed, toothless. Maxillary palpus 4-segmented, last segment bottle-shaped. Labial palpus with bean-shaped outwardly curved terminal segment inserted near midlength of obliquely truncate penultimate segment ( Fig. 25 ). Antennae long and slender, scape unmodified, pedicel smaller, little wider and longer than antennomere 3 ( Fig. 24 ). No antennal groove. Legs unmodified.

Pronotum wide and short, a continuous regular curve extends forward between the pointed rear angles, no front angles. The rear edge projects towards the scutellum. The surface is gently curved in the frontal plane from left to right margin, but straight in the sagittal plane, between front and rear margin ( Fig. 23 ). The scutellum is a small equilateral triangle. Elytra without costae, anterior portion of side margin slightly explanate. Entire dorsal side finely and irregularly punctate. Legs ambulatory, unmodified.

Ventral face ( Figs. 22, 24 ). The subgenal ridge runs close to the eye and meets a branch of the gular suture. Together they continue to the edge of the oral cavity. The prosternal process is blade-like, the tip a little enlarged, drop-shaped. The receiving mesoventral groove is rhomboid. The mesoventral process is very narrow, caudally finely divided. Metaventral process conical, discrimen visible on caudal 2/3 of metaventrite. Abdominal sternites unmodified, except female sternites 4–6 with paired pore plates with fine pilosity that are not easily observed. Terminal sternite indistinctly emarginate or truncate. The anterior portion of the elytral epipleura is flat, not grooved, but wider than the mesanepisternum.

Male. T8 large, caudal margin rounded, plate covered with microtrichia and interspersed true setae as small as the microtrichia (Fig. 32). S8 V-shaped, caudolateral lobes unpigmented and unsclerotized but with a few long straight setae (Fig. 28). T9 with strong apodemes continuing for some distance onto the plate. The antecosta is a thin angular sclerite connecting the apodemes. Plate membranous, no defined shape, bare. There are two large window-like transparent areas basally on the plate, between the antecosta and the caudal continuation of the apodeme. S9 is an unpigmented plate narrowing basally, with paired weak sclerite strips and slightly curved setae caudally. Tegmen (e. g., Figs. 34, 38) a spade-shaped plate from which the parameres diverge. They are flat, armed with teeth and spinules, mainly on the outside. At the base, each carries a movable sclerotized armed appendage. The pala lacks a sclerotized front edge, its lateral sclerites are separated, or connected only by some cartilage-like strip. The trigonium varies much between species but is always much shorter than the slender simple parameroids.

Female. Known of only T. victoriae , see there.

Note. The male genitalia of Tectocyphon follow a uniform pattern, it may be that in T. hispidus and T. victoriae the pala is normally closed by a cartilage-like strip, i.e., that the lateral spread of the disconnected sclerites is an artifact. Shortness of material precludes an examination. The broadly oval body with wide pronotum and wide elytral epipleura resembles the genus Eurycyphon which is more strongly domed. Also, the pronotum of Eurycyphon has a straight front margin between blunt distinct front angles, only the rear part of head is covered.

Etymolog y. Latin tectum, roof, cover, combined with the classical name, Cyph on, an allusion to the way in which the pronotum completely conceales the head.

Figures

FIGURES 21 – 26. Tectocyphon microphallus, n. gen., n. sp., male. 21 – 23, habitus; 24, head, ventral, labium and maxilla removed; 25, labium; 26, maxilla. 25, 26 to the same, 21 – 23 not to scale. ep, epipleura; es, episternum; gs, gular suture; sg, subgenal ridge.