Parachorius nudus ( Sharp, 1875 ) S. Tarasov, 2017

Tarasov, Sergei, 2017, A cybertaxonomic revision of the new dung beetle tribe Parachoriini (Coleoptera: Scarabaeidae: Scarabaeinae) and its phylogenetic assessment using molecular and morphological data, Zootaxa 4329 (2), pp. 101-149 : 133-134

Parachorius nudus ( Sharp, 1875) new combination

( Figs. 18 )

Cassolus nudus Sharp, 1875:40

Cassolus nudus ; Gillet 1911: 39

Cassolus nudus ; Boucomont & Gillet 1921: 4 Cassolus nudus ; Paulian 1945: 58

Panelus quadridentatus Balthasar, 1952: 223 (species inquirenda) Cassolus quadridentatus ; Balthasar 1963: 260 Cassolus nudus ; Balthasar 1963: 260

Cassolus nudus ; Masumoto, 1987: 127

Cassolus nudus ; Hanboonsong & Masumoto 2001: 135 Cassolus nudus ; Masumoto et al. 2012: 105

Type locality. Cambodia ( Cassolus nudus ); Hoa-Binh , Vietnam ( Panelus quadridentatus )

Distribution. The species is known only from the holotype specimen collected in Cambodia, which lacks any detailed information on the type locality.

Diagnosis and taxonomic notes. In external morphology this species is most similar to P. solodovnikovi , P. longipenis , and P. peninsularis . Reliable species identification in this group requires examination of the parameres. The squeezed aedeagus of the holotype, the only available specimen of this species, does not allow reconstructing the real shape of the aedeagus. This imposes problems on the identity of this species and its separation from the similar species. Although the aedeagus is squeezed, the examination suggests that its parameres seem to lack hornlike dorsal lobes that are present in P. solodovnikovi and P. longipenis . Given current state of knowledge, this indicates that P. nudus is a separate species. At the same time, due to squeezing the separation of the paramere shape between P. nudus and P. peninsularis does not seem possible. However, from the latter, P. nudus can be reliably distinguished by the modified first tooth of the protibia, where P. nudus is bifurcate, spatulate, bent downward, and notably larger than the second tooth with which the first tooth is almost merged. These facts support the species identity of P. nudus .

Panelus quadridentatus , the synonym of P. nudus , is described from Vietnam (“ Tonkin: Hoa-Binh, A. de Cooman leg.”). All studied material from Vietnam suggests that P. nudus does not likely occur there, which points out that P. quadridentatus is probably conspecific with either P. solodovnikovi or P. longipenis , which are known from the same collecting events. Unfortunately, the type of Panelus quadridentatus deposited in NMPC is probably lost ( Bezdek & Hajek 2011). Moreover, the original description of Panelus quadridentatus does not list any characters enabling reliable separation of this species from other Parachorius . Hence, being unable to examine the type and separate P. quadridentatus from other Parachorius , I follow Balthasar (1963) and tentatively treat P. quadridentatus as a synonym of P. nudus . The elucidation of P. quadridentatus identity needs further investigation and this species has to be formally regarded as species inquirenda.

The type of P. nudus is the only Parachorius known from Cambodia. Additional sample of Parachorius from Cambodia is needed to assess diagnosis and identity of P. nudus .

Description. Body. Body dark, length 4.8 mm. Elytra uniformly colored.

Head. Clypeus with two teeth, outer margin of each tooth distinctly notched basally.

Pronotum. Pronotum rounded laterally. Frontal angles rounded. Disc covered with punctures separated by 1.0– 1.5 puncture diameter(s). Pronotum in anterior-posterior direction notably shorter than elytra.

Elytra. Elytra covered with sparse punctures.

Wings. Wings normally developed.

Legs. Profemur with almost straight or sinuate anterior margin. Protibia with apical spur reaching protarsomere 2. First tooth notably modified in males, spatulate, bent downward and notably larger than second tooth, with which it almost merged; first tooth may look bifurcated as it is merged with denticles located between first and second teeth. Metafemoral posterior margin not serrate, simple, not modified. Metatibia slightly sinuate, inner margin denticulate with relatively small teeth, produced in small angle apically.

Metasternum. Transverse basal ridge of metasternum reduced and extremely short.

Aedeagus. Parameres symmetrical, simple, and narrowed toward apex (lateral view).

Material examined. Holotype of Cassolus nudus : Cambodia: 1 male, " Cassolus nudus type DS / Camb Mouhot [ Cambodia] / Ex Musaeo D.Sharp 1890 / G..J. Arrow vidit 1901 / Museum Paris ex. coll. R. Oberthur / Type / Holotypus Cassolus nudus S. Tarasov det. 2010 / Parachorius nudus S. Tarasov det. 2011 " ( MNHN).

Figures

FIGURE 18. Morphology of Parachorius nudus. (A, C) aedeagus, right lateral view (holotype). (B, D) aedeagus, left lateral view (holotype). (E) protibia (male, holotype). (F) habitus (male, holotype).