Parachorius semsanganus Tarasov & Keith

Tarasov, S. & Keith, D., 2011, Parachorius semsanganus sp. n. (Coleoptera, Scarabaeidae, Scarabaeinae) from Laos and its significance in the phylogeny of Oriental Deltochilini, ZooKeys 111, pp. 51-57 : 52-54

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Parachorius semsanganus Tarasov & Keith

sp. n.

Parachorius semsanganus Tarasov & Keith   ZBK sp. n. Figs 1-5

Type locality.

Laos, Xieng Khouang prov., Phou Sane Mt.

Material examined.

Holotype (NHMB), male bearing the following labels:

LAOS-NE, Xieng Khouang prov., 19°38.20'N, 103°20.20'E, Phonsavan (30 km NE): PHOU SANE Mt., 1420 m, 10.-30.v.2009, D. Hauck leg.

NHMB Basel, NMPC Prague Laos 2009 Expedition: M. Brancucci, M. Geiser, Z. Kraus, D. Hauck, V. Kubáň

HOLOTYPE Parachorius semsanganus S. Tarasov & D. Keith det. 2011

Paratypes. 9♀, same data as holotype; 2♂, same data as holotype but Z. Kraus leg.; 4♂, 3♀, LAOS-NE, Xieng Khouang prov., 19°37'N, 103°20'E; 19°38'N, 103°20'E, 30 km NE Phonsavan: Ban Na, Lam Phou Sane Mt., 1300-1500 m, 10.-30.v.2009, M. Brancucci leg.


Oval, convex, black, entirely shiny; mouthparts, antennae and legs red-brown. Dorsal body side covered with two types of punctures: larger (normal) punctures and very tiny punctures (which can be observed only under higher magnification of 40x or more) Dorsal and ventral body sides glabrous. Length 8.2-10.6

Male (Fig. 4).

Head flat, punctation fine; anterior margin notched medially; notch delimited by 2 prominent triangular obtuse teeth; clypeus laterad of each tooth very slightly notched; eyes completely divided by canthus into lower and upper lobes; lower lobes significantly larger than upper ones; genae and clypeus not distinctly separated from frons; genae rounded and protruding; antennae with 9 segments, antennal club with 3 segments.

Pronotum broadly trapezoidal, punctation fine, separated by 1-2 puncture diameters on disc, becoming slightly denser laterally. Lateral margins of pronotum flattened, arcuate, widest near base; lateral and anterior side marginate, posterior side not marginate; anterior angles obtuse; posterior angles rounded. Prothoracic fovea excavated, delimited by ridge reaching propleural lateral margin.

Elytra with eight striae, sublateral carina forming pseudepipleuron beyond eighth stria; epipleura narrow; interstriae flat with sparse, fine punctation.

Protibiae with three outer teeth; 1st tooth slightly thicker than two others; inner margin with two vertical teeth underneath, located approximately opposite to 2nd and 3 rd outer teeth; protibial apical spur acute, long, reaching middle or apical portion of 3rd tarsal segment; sometimes protibial teeth and apical spur abraded.

Metafemoral posterior margin with keel bearing indistinct and slight serration on top (Fig. 5). Metatibiae slightly curved, conspicuously denticulate on inner margin (Fig. 5, indicated with arrow); teeth are abraded in some specimens.

Pygidium with rather coarse, uniform, dense punctation.

Aedeagus (Figs 1-3) with converging, spatulate apices of parameres.


Similar to male but with the 1st protibial outer tooth slightly thinner than in males; metafemoral posterior margin not serrate; metatibial inner margin not denticulate.


All specimens of the type series look very similar to each other. Some variation may be observed in the shape of teeth on the metatibial inner margin, which are less expressed in some males due to abrasion.

Holotype (Fig. 4).

The holotype specimen lacks the tarsus of the right middle leg.

Differential diagnosis.

The new species is quite distinct among all other known species of Parachorius and Cassolus . It can be easily separated from them by the following unique set of character states: clypeus near outer side of each clypeal tooth very slightly notched, metatibial inner margin with large teeth (Fig. 5, arrowed), and aedeagus with spatulate apices which are largely bent inward (Figs 1-3).

Distribution and ecology.

The species is known from only 16 specimens of the type series collected across a range of altitudes between 1300-1500 m on Phou Sane Mt. of Xieng Khouang province in Laos.


The name of the new species is derived from the Latinized Lao words “syam” - link and “sanga” - spectacular. Its meaning "spectacular link" refers to the fact that this species represents a "morphological link" between the genera Parachorius and Cassolus .

Taxonomic notes.

Based on taxonomic concepts of the most recent monographic study dealing with Parachorius and Cassolus ( Balthasar 1963), the morphological differences between these two taxa can be summarized as follows: Cassolus are normally smaller than Parachorius ; the clypeus near the outer side of each clypeal tooth is usually deeply notched in Cassolus and not notched in Parachorius (very slightly notched in Parachorius semsanganus sp. n.); the metatibiae are curved in Cassolus and more or less straight in Parachorius (slightly curved in Parachorius semsanganus sp. n.); some Cassolus species have denticles on the inner metatibial margin, whereas the metatibial margin of Parachorius is not at all denticulate (distinctly denticulate in Parachorius semsanganus sp.n.). As can be seen from this combination of characters, Parachorius semsanganus sp. similar, on the one hand, to Parachorius and on the other hand to Cassolus (in particular to Cassolus gotoi Masumoto, 1986). A robust justification of the taxonomic placement of Parachorius semsanganus sp. n. requires an extensive phylogenetic analysis embracing both Parachorius and Cassolus . Such an analysis is currently in preparation and it may, in particular, result in the synonymy of Parachorius and Cassolus . Therefore to avoid potential nomenclatural changes in the future, we place the new species in the earlier described genus Parachorius.