Semigenetta thailandica, Wang & Jiangzuo & Grohé & Chaimanee & Jaeger, 2024

Wang, Xiaoming, Jiangzuo, Qigao, Grohé, Camille, Bonis, Louis de, Chaimanee, Yaowalak & Jaeger, Jean-Jacques, 2024, A review of the Asian Semigenetta Helbing, 1927 (Viverridae, Feliformia, Carnivora) with a description of two new species, Semigenetta qiae n. sp. from South China and Semigenetta thailandica n. sp. from Thailand, Comptes Rendus Palevol 23 (26), pp. 417-432 : 427-428

Semigenetta thailandica n. sp.

( Fig. 7; Table 1)

urn:lsid:zoobank.org:act:C4A11D4B-396E-4324-B7AD-188FB6C8DEB1

Semigenetta cf. steinheimensis – Bonis et al. 2021: 324, fig. 3.

MATERIAL EXAMINED. — Holotype. Northern Thailand. Lampang Province, Mae Moh Basin ; MM-106 , partial left dentary with c-p1 alveoli, p2-m1, and m2 alveolus.

DIAGNOSIS. — Middle-sized Semigenetta , low ascending ramus of dentary, large masseteric fossa, relatively low premolars, p4 clearly larger than p3, enlarged accessory cuspids on p3-p4, weak accessory cuspids on p2, small diastema between p2-p3, talonid of m1 slightly narrower than trigonid and with cristid obliqua directed mesiodistally. Differs from other middle-sized Semigenetta species: S. sansaniensis by p4 clearly larger than p3, p2 less symmetric, larger accessory cuspids, smaller p2 mesial cuspid; S. qiae n. sp. by shorter and lower premolars relative to m1, p3 clearly smaller than p4, diastema between p2-p3, p2 with smaller distal accessory cuspid and with much smaller mesial one, wider extent of the masseteric fossa.

ETYMOLOGY. — The species name refers to the country from which the holotype was found.

TYPE LOCALITY. — Northern Thailand, Lampang Province, Mae Moh Basin, Na Khaem Formation in the K coal zone of the Mae Moh coal mine ( Bonis et al. 2021). The Q and K coal zones of the Na Khaem Formation were magnetically correlated to C5AAr ( Coster et al. 2010), with a GTS2020 ( Raffi et al. 2020) calibrated age of 13.363 -13.183 Ma in the late middle Miocene.

DESCRIPTIONS

See Bonis et al. (2021) for original descriptions and Figure 7 for a new illustration of the holotype.

COMPARISON AND DISCUSSION

Although the top of the ascending ramus is broken, the remaining portion seems to suggest a short ascending ramus, i.e., the posteriorly curved anterior rim of the masseteric fossa is largely intact. If this is correctly interpreted (and confirmed by better materials in the future), it is perhaps the most remarkable feature, which is somewhat felid-like, in contrast to other European species that preserve this part of the morphology. Otherwise, the morphology of this species is generally consistent with Semigenetta .

In their description of MM-106, Bonis et al. (2021) referred it to Semigenetta cf. S. steinheimensis ( Fraas 1870) because of its similarity in size and age relationship. They used this occurrence in Thailand as an example of long-distance migration from Europe, and they speculated that this species could have dispersed along a corridor around the Tibetan Plateau through either a Central Asian or a southern Asian route into Thailand during the middle Miocene.

Shortly after Bonis et al. (2021), Kargopoulos et al. (2021) commented that the newly published mandible from Thailand fits the generic diagnosis of Semigenetta , particularly regarding its m1. However, they pointed out differences in its premolars with lower-crowned and shorter main cuspids as well as lower but larger anterior and posterior accessory cuspids. In their opinion, these premolar differences indicate a new species distinct from S. sansaniensis (including S. steinheimensis , which was synonymized under S. sansaniensis within their systematic scheme). Except the crown height in the main cuspid, the enlarged accessary cuspids in premolars in the Thai form is consistent with those in S. qiae n. sp. If the enlarged premolar accessory cusps are considered shared derived character, then a distinct South China-Southeast Asia clade may exist. Mein & Ginsburg (1997) illustrated a “? Semigenetta sp. ” from the middle Miocene Li Mae Long of Thailand. However, of the three isolated teeth (identified as right p3, right dP4, and right dp3), none preserve enough diagnostic characters to be certain of their identification. Bonis et al. (2021) included the Li Mae Long record in Semigenetta .