Phoberus nyikanus Strümpher, 2017

Strümpher, Werner P. & Scholtz, Clarke H., 2017, A new brachypterous species of Phoberus MacLeay (Coleoptera: Trogidae) and status changes of species in the East African P. nigrociliatus group, Zootaxa 4216 (3), pp. 292-298 : 293-295

Phoberus nyikanus Strümpher , new species

( Figs. 1A –D, 2A)

Type material. Holotype: (1♂: NCSA): MALAWI / SE1033BD / Nyika National Park / 2.iii.1987 / 2607 m. / J. & A. Londt / Nganda summit—grassveld (typeset on white rectangle). The aedeagus of the holotype is placed separately in a transparent genital vial. Dissected metathoracic wing set separately on white cardboard rectangle. Condition of Holotype: Good, except that tarsi on protibia are missing . 2 Paratypes: (1♂, 1♀: TMSA): Chapolo for[est] (handwritten) / Nyika National Park / Malawi / 2.i.1981 (handwritten) / Coll: C.O. Dudley (typeset on white rectangle) . 1 Paratype: (♀: UPSA): Chilenda (handwritten) / Nyika Nat [ional] Park / Malawi / 31.xii.1980 (handwritten) / Coll: C.O. Dudley (typeset on white rectangle) // Grassland (typeset on white rectangle) . 1 Paratype: (♀: UPSA): M9724 / Nyika Nat [ional] Park / Malawi / iv.1976, V. Taylor / 8000 [feet] / (handwritten on white rectangle). Specimens bear new type labels: HOLOTYPE [or PARATYPE] / Phoberus nyikanus Strümpher, 2016 (printed on red rectangle).

Diagnosis. This new species is morphologically similar to other members in the group, Phoberus nigrociliatus (Kolbe) new status ( Fig. 3A –C), P. nyansanus (Haaf) new status ( Fig. 4A –C), and P. nyassicus (Haaf) new status ( Fig. 5A –C). However, it can be reliably distinguished from other members by the presence of low, semicontinuous ridges (partially fused tubercles) on the even-numbered costae ( Fig. 1A ), whereas in the other three species the tubercles are distinct, evenly spaced, and not fused ( Figs. 3A , 4A , 5A ). Furthermore, P. nyikanus lacks the distinct longitudinal ridges marking intercostal margins, which are prominent in the other three species ( Figs. 1A , 3A , 4A , 5A, 5 C).

Holotype description. Colour: Black. Size: length 15.1 mm, width (across humeri) 6.9 mm. Head: Clypeus triangular, apical portion deflexed; lateral margins with pointed setae; surface of clypeus and frons punctate; frons with raised, rounded setose ridges; antennal scape black, elongate, with long, black setae; pedicel attached to apex of scape; club black, velutinous ( Fig. 1A –B). Pronotum: attenuate anteriorly, sides broad, lateral margins irregular, with fringes of dark brown setae; surface coarsely punctate; median depression distinct and except for median obstruction stretches over entire length of pronotum; anterior half of median depression shallow, posterior half deeper and broader; discal area raised; discal ridges rounded, broad anteriorly, attenuate anteriorly to short narrow ridge; median basal tubercles and lateral basal tubercles present, lateral basal tubercle partially fused to anterolateral tubercle; posterior margin with dense fringe of flat setae; pronotal ridges and tubercles with setae ( Fig. 1A –B). Scutellum: Oval , as wide as long, sunken basally ( Fig. 1A ). Elytra: humeral calli present, reduced; lateral margins smooth to slightly irregular; sutural margin raised, with small, round to slightly elongate tubercles with tufts of black setae; even-numbered costae distinct, tubercles partially fused to form low, continuous ridges with regular tufts of setae; odd-numbered costae with small tubercles; indistinct/vestigial longitudinal ridges mark intercostal margin, and intercostal punctures round to evenly undulate with transverse ridges between them; elytral profile convex, attaining maximum height behind middle ( Fig. 1A –B). Metathoracic wing: wing length approximately equal to length of elytron; apical region distal to apical hinge reduced in size, RP branches incomplete and lacking sclerotization ( Fig. 2 A). Legs: protibia bifid, outer margin with 3 small, median teeth, inner margin with long, dense setae, tibial spur as long as, or longer than, third tarsomere; mesotibia and metatibia with long, dense, black setae, 2 apical spurs on inner margin, spurs as long as, or slightly longer, than first tarsomere; tarsomeres ventrally with sparse setae, claws simple ( Fig. 1A ). Male genitalia: See Fig 1 C.

Variation (1 male and 3 female paratypes). Size: length 10.9–14.8 mm, width (across humeri) 5.6–6.9 mm. Legs: outer margin with 2–3 small median teeth. The external morphology of males and females is identical.

Distribution. Nyika Plateau in northern Malawi ( Fig. 6).

Etymology. This species is named for the Nyika Plateau, where the type series was collected.

Comments. Examination of the metathoracic wings of Phoberus nyikanus ( Fig. 2 A) and P. nyassicus (Haaf) ( Fig. 5 D) clearly shows these two species to be in the early stages of flight loss (stage 1 and 2; See Browne et al. 1993). In both species the region distal to the apical hinge is reduced in size, the wing membrane is thin, and the RP branches are incomplete and lack the typical dense sclerotization; also the anal region of the metathoracic wing shows some degree of reduction. The metathoracic wings of beetles are used for propulsion during flight (posteromotorism) and, although the flight capability of the two species is not known, we can assume that it is greatly compromised by the degree of wing reduction that likely renders the two species flightless.

Figures

FIGURE 1. A, Dorsal habitus of Phoberus nyikanus holotype; B, lateral habitus of P. nyikanus holotype; C, dorsal and lateral views of the aedeagus of P. nyikanus holotype; D, holotype label.

FIGURE 2. Extent of metathoracic wing reduction in A, Phoberus nyikanus, a brachypterous species; compared to B, Phoberus planicollis (Haaf), a fully-winged, South African species of similar size (15 mm).

FIGURE 3. A, Dorsal habitus of Phoberus nigrociliatus; B – C, dorsal and lateral views of the aedeagus of P. nigrociliatus.

FIGURE 4. A, Dorsal habitus of Phoberus nyansanus; B – C, dorsal and lateral views of the aedeagus of P. nyansanus.

FIGURE 5. A, Dorsal habitus of Phoberus nyassicus; B, dorsal and lateral views of the aedeagus of P. nyassicus; C, elytral sculpture of P. nyassicus; D, metathoracic wing of P. nyassicus.