Petrocyphon lacteus, Zwick, 2016

Zwick, Peter, 2016, Australian Marsh Beetles (Coleoptera: Scirtidae). 9. The relations of Australasian Ypsiloncyphon species to their Asian congeners, additions, mainly to Petrocyphon and Prionocyphon, and a key to Australian genera of Scirtinae, Zootaxa 4085 (2), pp. 151-198 : 161

Petrocyphon lacteus , n. sp.

(Figs 16–20)

Type material. 1♂ Holotype: AUSTRALIA, TAS Milkshake Hills Forest Reserve 41°05'S, 145°09'E 10 February 1992 \ Tom Gush in leaf litter Tom Gush Collection ( ANIC).

Habitus. Long and slender, parallel-sided, with protruding head and long, thick antenna. BL 1.6 mm, BL/BW ~2.2, PW corresponds to ~80% of BW, HCW is ~80% of PW, length of antenna ~80% of total length. Entirely light ochre, pilosity rather short. Granular punctures on head and pronotum moderately coarse, normal punctures on elytra of similar size near base but become successively finer rearwards, until very fine near apex. Pronotum subcordiform, rounded sides distinctly beaded, no setae projecting over the edge.

A member of the P. antarcticus- group with very thick male antennae. Terminalia generally similar to the other two species in the group.

Male. Segment 8 and T9 (Figs 16, 17) as in P. antarcticus Watts and P. wattsi Zwick. S 9 with more strongly divergent caudal lobes including a wide regularly U-shaped space between them (Fig. 18), with a few indistinct sensilla on tips, basal sclerites parallel and wider apart than in relatives. Tegmen with oval notch between parameres, similar to P. antarcticus but stouter, lateral flanges extending further forward (Fig. 19). Penis (Fig. 20) with narrow mushroom-shaped trigonium, deep notches separate it from the parameroids. Apex with a cap-like sclerotization from which a thin spur extends forward. Parameroids intermediate between relatives in length but (unlike in relatives) very wide, overlapping at base and meeting at apex. Surface with several oblique crests terminating in a small tooth on lateral edge. Endophallus distinctive, with two bands of strong spines with recurved tips, a transverse group of more slender spines in front of these lateral bands, plus a loose median band of extra long slender spines in front.

Female. Unknown.

Note. The three related species probably originated from a common ancestor by geographical separation, with P. antarcticus in the central highlands, P. wattsi in the east (Blue Tiers), and P. lacteus on the Milkshake Hills in the northwest.

Etymology. The name of the type locality suggested the species name, the Latin adjective lacteus , of milk, related to milk, or white as milk.