Calvarium (Calvarium) australiense, Zwick, Peter, 2014

Zwick, Peter, 2014, Australian Marsh Beetles (Coleoptera: Scirtidae). 6. Genera Calvarium Pic, Papuacyphon Zwick, and Ypsiloncyphon Klausnitzer, Zootaxa 3846 (1), pp. 1-41 : 3-6

Calvarium (Calvarium) australiense , n. sp.

( Figures 1−5 , 10−13 )

Type material. Holotype: ♂ “Groote Eylandt N.B.Tindale“. Paratypes: 1♂ with the same data; 1♂ “N. Queensland Blackb's Coll.” (all SAMA; the specimens had been previously dissected and are in poor shape).

Diagnosis. A convex species distinguished by its terminal segments and genitalia, mainly the deeply excised U-shaped T8, the pincer-like T9, and by the large paramedian tegminal lobes ending in a long straight spine.

Habitus (no intact specimen available). BL ~ 3.3 mm, BL/BW ~1.6. Strongly convex, shining, pilosity fine. Head and pronotum finely, elytra densely and much more coarsely punctate. Pronotum with strongly projecting front angles, front margin straight. Chestnut brown, appendages yellowish brown.

Head strongly transverse, twice as wide across eyes as long from occipital foramen to front of frontoclypeus. Head capsule width correponds to about 60% of total body width. Front edge of frontoclypeus and oral area very narrow.

A deep antennal sulcus between the mouthparts and the eye is laterally delimited by a continuation of the curved anterolateral edge of the frontoclypeus which turns into a low ridge above the antennal insertion. The ridge curves towards the eye, then down along the front edge of the eye, leaving a small triangular gena.

There are two separate ridges beneath the eye. The upper subocular ridge ( Fig. 1 , sor) begins below the triangular gena and runs backward a short distance below the eye. Caudally, it diverges from the eye and tapers away in the area covered by the pronotal lobes. In anterior view this ridge forms the side edge of the head capsule. Beneath it, on the underside of the head, begins the subgenal ridge ( Fig. 1 , sgr). It runs backward far ventrally from the eye and eventually meets the occipital ridge.

The gular sutures are shorter than 1/3 of the distance between them. Sutures indistinct in front of the tentorial invaginations, reappearing a short distance before the rear edge of the mentum.

Antenna a little longer than head width. Scape an almost circular disc with sharp front edge. Resting position as described for the genus. Distal flagellar segments subcylindrical, about 2.5 times longer than apically wide.

Labrum narrow, sides parallel, rounded front margin with a very shallow median excision ( Fig. 3 ). Mandibles symmetrical, slender, with pointed tip and one large subterminal tooth ( Fig. 2 ). Contour undulating between tooth and flat, bare, shining molar area. Terminal segment of maxillary palpus about twice as long as penultimate segment, tubular, indistinctly concave, apex blunt ( Fig. 4 ). Last segment of labial palpus slender, concave, standing near the inner edge of the apically inflated penultimate segment ( Fig. 5 ).

Ventral side as for genus.

Male. T8 and T9 ( Figs. 10, 11 ) with strong straight apodemes. T8 with deep U-shaped notch as wide as 1/3 of total width. Each lobe covered with sharp denticles or asperities. T9 with convergent apodemes ending in sharp tips separated by a narrow gap, resembling pliers or pincers. S8, S9 not found in preparations.

Penis ( Fig. 12 ) consisting of two narrowly separated flat long plates supporting a strongly sclerotized mushroomshaped cap. On its convex surface articulate the knee-shaped bases of the parameroids, details concealed by strong muscles extending between the cap and the front end of the plates. Parameroids flat, gently curved, with narrow shaft which widens caudally and ends in an obliquely truncate finely serrate axe-like apex.

Tegmen with a soft, short base from which the parameres originate ( Fig. 13 ). Each paramere is deeply divided into a curved external spine and a flat medial lobe rising from a curved base, with an inward projecting hard condyluslike knob situated medially near base. Approximately parallel over most of length, then narrowed strongly, with a tiny denticle on outside. Terminal fifth forming a long spine in straight continuation of the sclerotized medial edge.

Female. Unknown.

Notes. The antennal sulcus, the resting position of the antennae, the prosternal process, width and shortness of mesoventrite, and the male genitalia place the new species in the genus Calvarium (Ruta 2010) . A subocular ridge in addition to the subgenal ridge was never described, but occurs also in C. superbum (below) as well as in other species of Calvarium (s. str.) (Ruta, pers. communication).

The male genitalia are very similar to several other species. Caudal parameroids whose basal condyli rest on a hard, cap-like part of penis connected by muscles to the anterior penis edge occur in all species whose genitalia have been described. Axe-shaped parameroids occur in several species, a deeply notched or even completely divided and often spinulose T8 occurs in several species. T9 is usually much reduced. The tegmen is often divided into slender lateral spikes and a pair of variably shaped paramedian processes.

The most similar species is C. johorense (Yoshitomi & Sato 2004) from Malaysia which shares the pincer-like T9. However, it is readily distinguished by the rounded overall contour of T8 and especially by the tegmen which has long lateral rods but short club-shaped paramedian lobes. The very large paramedian tegminal lobes ending in a long straight spine distinguish C. australiense from the described genitalia of all congeners.

Etymology. The name is a Latin adjective, nominative singular, neutrum, meaning “Australian”.

Figures

FIGURES 1 − 9. Calvarium spp., head morphology. 1 – 5, C. (C.) australiense, n. sp.; 6 – 9, C. (Calvariellum) hamifer, n. sp.: 1, 6, ventral views of mounted heads; 2, left mandible, dorsal view; 3, labrum; 4, maxillary palpus; 5, labium; 7, frontal view, slightly from ventral side, diagrammatic, right antenna removed; 8, maxillary palpus; 9, labial palpus. Figures 2 – 5 and 8, 9 to the same scale, respectively; Fig. 7 not to scale. Abbreviations: af, antennal foramen; as, accessory suture; asu, antennal sulcus; la, labrum; md, mandible; sgr, subgenal ridge; sor, subocular ridge; trs, transverse suture.

FIGURES 10 − 13. Calvarium (Calvarium) australiense, n. sp., male: 10, T 8; 11, T 9; 12, penis; 13, tegmen and parameres. All to the same scale.