Rowsonia 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 : 700-701

Rowsonia Páll-Gergely , new genus

Type species. Ennea beddomei W.T. Blanford, 1881 ( Fig. 12J–Q ).

Diagnosis. Shell small to large, smooth to regularly ribbed, slender conical. Parietal callus well-developed to weak. Basal swelling not developed. Parietal lamella elongated inside, outer end usually straight, outer portion curves towards palatal wall. Inner portion curves towards columella. Palatal wall with an upper palatal tooth that faces the curved parietal lamella. There are two to three deeply situated, elongated additional folds (upper, middle, and lower palatal folds). Columellar lamella well-developed, sharp, oblique to shell axis. See Fig. 1O for explanation.

RAFFLES BULLETIN OF ZOOLOGY 2020

Differential diagnosis. Rowsonia , new genus, differs from Ennea (compared only with the type species) in the following characters: the shell shape of the new genus is conical, whereas it is ovoid in Ennea ; the parietal lamella is short in Ennea , inner and outer portions of different orientation cannot be recognised; columellar lamella of Ennea is weak, low, and not visible from straight view to the aperture; the deeply situated folds are much longer than those of Rowsonia , new genus, and they correspond with grooves on the dorsal (“neck”) region.

Pupennea , new genus is ovoid, possesses two teeth on the columellar side (columellar lamella and denticle), has a shorter parietal lamella, has a complex structure consisting of the upper and lower parietal teeth, and lacks deeply situated palatal folds.

Sinoennea species are usually elongate ovoid and cylindrical in shell shape, lack any deeply situated parietal/basal folds, usually have a prominent basal swelling and there is a depression that corresponds with the upper palatal tooth. See under Platylennea , new genus.

Included species. Rowsonia beddomei (W.T. Blanford, 1881) , R. canarica (W.T. Blanford, 1869) , R. pirriei (L. Pfeiffer, 1855) , R. sculpta (W.T. Blanford, 1869) , and R. turricula (W.T. Blanford, 1899) .

Etymology. This genus is dedicated to and named after Ben Rowson (National Museum of Wales), a specialist of the Streptaxoidea . Grammatical gender: feminine.

Distribution. Southern India ( Fig. 10 ).

Remarks. The most closely related genus is probably Platylennea , new genus, which also inhabits southern India. The distinction of the two groups is clear, and thus, these two groups should be separated as distinct genera. However, the morphological diversity of Sinoennea is still larger than the difference between Platylennea , new genus and Rowsonia , new genus.

Figures

Fig. 12. A–G, Platylennea subcostulata (W.T. Blanford, 1881), NHMUK 1892.4.9.46–56, specimen1; H–I, NHMUK 1892.4.9.46–56, specimen2; J–Q, Rowsonia beddomei (W.T. Blanford, 1881), NHMUK 1912.4.16.99. All scales represent 1 mm; scale “a” refers to fig. A, scale “b” refers to figs. B–I, scale “c” refers to fig. K, scale “d” refers to figs. L–Q.

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.