Semigenetta Helbing, 1927

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 : 420-421

Genus Semigenetta Helbing, 1927

TYPE SPECIES. — Viverra sansaniensis Lartet, 1851 .

INCLUDED SPECIES. — Semigenetta sansaniensis ( Lartet, 1851) , S. cadeoti Roman & Viret, 1934 , S. laugnacensis ( Bonis, 1973) , S. elegans Dehm, 1950 , S. grandis Crusafont Pairó & Golpe Posse, 1981 , S. huaiheensis Qiu & Gu, 1986 , S. qiae n. sp., and S. thailandica n. sp.

GEOGRAPHIC AND CHRONOLOGICAL DISTRIBUTION. — Late Agenian (MN2b) to late Vallesian (MN10) of Europe; Shanwangian (early Miocene) and Baodean (late Miocene) in China; late middle Miocene of Thailand (Q-K coal zone of the Mae Moh Basin, 13.4-13.2 Ma).

EMENDED DIAGNOSIS. — Mandible bearing a deep masseter fossa, long and narrow angular process, canine with a well-marked buccal groove; a p4 with marked anterior and posterior accessory cuspids; reduction of m1 talonid, hypoconid present, m1 entoconid and hypoconulid absent or present as a low ridge, m2 reduced; loss of M2 ( Bonis et al. 2021; Kargopoulos et al. 2021).

REMARKS

Early feliform carnivorans can be divided into long-snouted (dolichocephaly) and short-snouted (brachycephaly) forms ( Hunt 1998). The dolichocephalic feliforms are unusual because feliforms often trended toward short snout and hypercarnivory. Examples of long-snouted feliforms include the extinct Haplogale Schlosser, 1887 from the Quercy fissures and the modern genet Genetta . The long snouts and jaws with diastemata between premolars probably represent a derived feature for some genet-like feliforms, including the extinct Haplogale ( Hunt 2001) . Such a lengthened rostrum may be analogous to early North American canine canids, such as Leptocyon Matthew, 1918 and its living canine descendants (Wang X. et al. 2008; Tedford et al. 2009).

Our knowledge of Semigenetta is still quite poor and comparisons with other small feliforms are limited to fragmentary jaws and teeth. Although no intact skull is known, Semigenetta generally has a slender jaw but its premolars are not separated by long diastemata. Exactly how Semigenetta is (or is not) related to the living genet has not been closely examined, althoughHelbing (1927) regarded his newly erected Semigenetta as representing a small group of fossil genets in Europe. The loss of the M2 and a short m 2 in all known species of Semigenetta suggest that this genus is not trending toward dolichocephaly as does Genetta , and lacking a shared derived character, Semigenetta and Genetta may or may not be closely related to each other.

The genera Genetta and Semigenetta represent some of the most generalized forms in the family Viverridae . They lack some of the advanced dental characters shown in hypocarnivorous, bunodont paradoxurines and related forms in Africa, such as Kichechia Savage, 1965 ( Savage 1965), Orangictis Morales, Pickford, Soria & Fraile, 2001 ( Morales et al. 2001; Morales & Pickford 2011), Tugenictis Morales & Pickford, 2005 ( Morales & Pickford 2005, 2011), Pseudocivetta Petter, 1967 ( Petter 1967, 1973), Kanuites Dehghani &Werdelin, 2008 ( Dehghani & Werdelin 2008; Werdelin 2019), Ketketictis Morlo, Miller & El-Barkooky, 2007 ( Morlo et al. 2007) and in Asia, Mioparadoxurus Morales & Pickford, 2011 ( Petter 1967, 1973; Morales & Pickford 2011) and Siamictis Grohé, Bonis, Chaimanee, Chavasseau, Rughumrung, Yamee, Suraprasit, Gilbert, Surault, Blondel & Jaeger, 2020 ( Grohé et al. 2020). Similarly, the southeast Asian otter civet ( Cynogale Gray, 1837 ) also has hypocarnivorous molars ( Gervais 1854: 29), and evidently not related to the Lufeng form, although, according to Grohé et al. (2020), it is related to another Lufeng viverrid described by Qi (2004), Lufengictis peii Qi, 2004 . Among Asian records, Lydekker (1884) described Viverra bakerii Lydekker, 1884 and V. durandi Lydekker, 1884 from the Siwaliks of Pakistan, the latter being placed in Vishnuictis durandi ( Lydekker, 1884) by Pilgrim (1932) and Colbert (1935). Both of these species have an unreduced M2 and thus easily distinguished from Semigenetta . Most recently, Grohé et al. (2020) erected a new genus Siamictis within the subfamily Paradoxurinae from the middle Miocene of Thailand.

Véron (2010) published the latest molecular relationship of viverrids, in which subfamilies Genettinae and Viverrinae are sister groups. Morphological characters are seen as highly convergent given the constraint of molecular relationships, although the above sister relationship is recovered without molecular constraint ( Gaubert et al. 2005). How fossil taxa are related to this phylogenetic framework of living viverrids has not been explored ( Véron 1995). With the exception of the loss of M2 (a character that independently occurs numerous times among carnivorans), dental morphology of Semigenetta is largely primitive, as in most stem feliform carnivorans.

From the deep-history paleontologic perspective, Hunt (2001) had envisioned a lineage of the extinct Palaeoprionodon with living linsangs ( Prionodon Horsfield, 1822 and Poiana Gray, 1864 ). However, modern molecular phylogeny suggests that Prionodon and Poiana do not belong to the same clade, but Poiana was at the base of a Poiana - Genetta clade ( Veron 2010), implying greater complexities than can be discerned from the fossil records only.

Heizmann (1973: fig.22) remarked about the increasing body size among European forms, a trend also echoed by Golpe-Posse (1981) and Bonis (1994). In his synthesis of the contents of Semigenetta from the Miocene of Europe, Bonis (1994) recognized five species of roughly increasing size: S. laugnacensis ( Bonis 1973) from Laugnac, France (MN2b), S. elegans from Wintershof-West, Germany (MN3), S. sansaniensis ( Lartet, 1851) from Sansan, France (MN6), S. steinheimensis Fraas, 1870 from Steinheim am Albuch, Germany (late MN7-8), and S. grandis Crusafont & Golpe-Posse, 1981 from Castell de Barbará, Spain (MN9). This systematic scheme was later adopted by Bonis et al. (2021), except Semigenetta elegans in Bonis (1994) becomes S. gracilis Dehm, 1950 in Bonis et al. (2021). The above species generally increase in body size, following a similar theme by Bonis (1994). For those species that do not fall in this trend, such as S. cadeoti Roman & Viret, 1934 and S. ripolli Petter, 1976 , Bonis et al. (2021) suspected that they might belong to other genera. Shortly after the above, Kargopoulos et al. (2021) did a review of Eurasian Semigenetta , in which they recognized five species.

Helbing’s (1927) original type species of Semigenetta is S. repelini from Captieux in southwestern France. Heizmann (1973), however, remarked that the Captieux sample is indistinguishable from S. sansaniensis , which had priority. Bonis (1994: 87) agreed with Heizmann’s assessment and further pointed out that accepting such a synonym would leave the genus Semigenetta without a type species and logically should be discarded. To avoid such an awkward situation and appealing to prevailing (greater than half a century) usage, Bonis (1994) proposed to conserve Semigenetta by designating Viverra sansaniensis Lartet, 1851 as its type species, whose holotype is MNNH Sa 813. Bonis’ proposal of fixing of the type species appears to be a valid taxonomic action because V. sansaniensis is eligible for type fixation as the species was originally included in Helbing’s discussion (article 67.2 of International Commission on Zoological Nomenclature 1999).