Platylennea Páll-Gergely, 2020

Páll-Gergely, Barna, Hunyadi, András, Grego, Jozef, Sajan, Sheikh, Tripathy, Basudev & Chen, Zhe-Yu, 2020, A review of the Diapheridae (Gastropoda: Eupulmonata: Streptaxoidea), with special emphasis on India and Myanmar, Raffles Bulletin of Zoology 68, pp. 682-718 : 696-697

Platylennea Páll-Gergely , new genus

Type species. Ennea subcostulata W.T. Blanford, 1881 .

Diagnosis. Shell reminiscent of members of Aciculidae (glossy, elongate conical); umbilicus entirely closed. Peristome discontinuous, parietal callus only indicated as transparent calcareous layer. Parietal lamella well-developed, complex, long, running deep inside, its outer end bent towards the palatal wall, and also has a blunt projection in the other side, resulting in a bifurcated outer end. Palatal wall with a tiny upper parietal denticle that is situated on the peristome. There are two basal denticles (upper and lower basal denticle) of comparable size, sometimes connected with a ridge. Lower basal denticle situated on or very close to the peristome, whereas the upper basal denticle (the one situated closer to the palatal tooth) situated somewhat deeper. Columellar lamella well-developed, semilunar, sharp, bladelike, slightly oblique to the shell axis. There is an additional tiny, blunt denticle (columellar denticle) on the columellar lip. No deeply-situated folds or denticles present. See Fig. 1I, J for explanation.

Differential diagnosis. Platylennea , new genus, differs from Ennea based on the conical (not ovoid) shell shape, the long and complicated parietal lamella, the absence of deeply situated plicae and the strong columellar and basal/ lower parietal barriers.

This new genus mainly differs from Rowsonia , new genus, in the arrangement of the apertural barriers. Namely, Platylennea , new genus, has two basal denticles situated close to the peristome edge, whereas Rowsonia , new genus, has three horizontal, deeply situated palatal folds (for information on their homologies, see Results and Table 1). Furthermore, Platylennea possesses a small columellar denticle anterior to the columellar lamella, and the prominent parietal lamella is bifurcated near/at its outer end.

Platylennea , new genus, has an elongate conical shell shape and a complicated, long parietal lamella, whereas the shell of Pupennea , new genus, is ovoid and its parietal lamella is short. Furthermore, the latter genus possesses a strongly developed, complex structure on the parietal side, in the position of the upper parietal tooth of Platylennea , new genus.

Sinoennea species are mostly elongate ovoid and cylindrical, with ovoid-rectangular aperture and well-developed callus. In Sinoennea there is an upper and lower palatal tooth which are in contact with each other. In contrast, Platylennea , new genus, has an upper palatal tooth and two basal denticles. The upper basal denticle of Platylennea , new genus, is probably homologous with the lower palatal denticle of Sinoennea . Furthermore, Sinoennea has a depression on the lateral side behind the reflected peristome corresponding with the lower palatal denticle. In the absence of a lower palatal denticle in corresponding position, there is no such depression behind the peristome of Platylennea , new genus.

Included species. Platylennea exilis (W.T. Blanford, 1881) , P. levis ( Peile, 1935) , P. macrodon (W.T. Blanford, 1881) , and P. subcostulata (W.T. Blanford, 1881) .

Etymology. The name Platylennea is the combination of the generic names Platyla Moquin-Tandon, 1856 , which the new genus resembles, and Ennea H. Adams & A. Adams, 1855 , which is a generic name that used to be widely used for high-spired Streptaxidae . Grammatical gender: feminine.

Distribution. Southern India ( Fig. 10 ).

Figures

Fig. 1. Nomenclature of the apertural barriers. A–H, Sinoennea; I, J, Pupennea, new genus; K, L, Sinoennea fartoidea; M, N, Platylennea, new genus; O, Rowsonia, new genus; P, Gulella (Huttonella). Abbreviations: BK, basal keel; BS, basal swelling; BT, basal tooth; CD, columellar denticle; CL, columellar lamella; CTd, depression corresponding with the columellar lamella; IBD, inner basal denticle; ICE, inner columellar edge; LBD, lower basal denticle; LPF, lower palatal fold; LPT, lower palatal tooth; LPTd, depression corresponding with the lower palatal tooth; MPF, middle palatal fold; OBD, outer basal denticle; PL, parietal lamella; PT, palatal tooth; S, sinulus; UBD, upper basal denticle; UPF, upper palatal fold; UPT, upper palatal tooth.

Fig. 10. Distribution of Parasinoennea, new genus, Sinoennea Kobelt, 1904, Pupennea, new genus, Platylennea, new genus, and Rowsonia, new genus.