Endothyrella tricarinata (Gude, 1897)

Pall-Gergely, Barna, Budha, Prem B., Naggs, Fred, Backeljau, Thierry & Asami, Takahiro, 2015, Review of the genus Endothyrella Zilch, 1960 with description of five new species (Gastropoda, Pulmonata, Plectopylidae), ZooKeys 529, pp. 1-70 : 43

Taxon classification Animalia Pulmonata Plectopylidae

Endothyrella tricarinata (Gude, 1897) Figure 13 E–F

Endothyrella tricarinata 1897b Plectopylis plectostoma var. tricarinata Gude: Science Gossip, 3: 275, figs 40 a–b. [ “Bengal”].

Endothyrella tricarinata 1897g Plectopylis plectostoma var. tricarinata , - Gude: The Journal of Malacology, 6: 45, fig. 2.

Endothyrella tricarinata 1899c Plectopylis (Endothyra) plectostoma var. tricarinata , - Gude: Science Gossip, 6: 148.

Endothyrella tricarinata 1899d Plectopylis (Endothyra) plectostoma var. tricarinata , - Gude: Science Gossip, 6: 176, 177.

Endothyrella tricarinata 1901 Plectopylis plectostoma var. exerta Gude new synonym: The Journal of Malacology, 8: 49, figs 5 a–d. ["Khasi Hills: Assam"].

Endothyrella tricarinata 1914b Plectopylis (Endothyra) plectostoma var. tricarinata , - Gude: The Fauna of British India …: 83, figs 32 a–b. [ “Bengal”, "Khasi Hills"].

Endothyrella tricarinata 1914b Plectopylis (Endothyra) plectostoma var. exerta , Gude, The Fauna of British India …: 83-84, figs 33 a–d.

Types.

Bengal, coll. MacAndrew ex coll. Benson, UMZC 102170 (2 syntypes of Plectopylis plectostoma var. tricarinata , Figure 13E); Khasia Hills, ex Nissor (?), NHMUK 1922.8.29.50. (syntype of Plectopylis plectostoma var. exerta , Figure 13F).

Additional material examined.

India, Khasia Hills, K4.30, coll. Rolle, NHMW 50854/2; Assam, Khasia Hills, coll. Bosch, ex coll. Rolle, SMF 172073/3; Assam, Cherrapoonjee, coll. Jetschin, ex coll. Gude 1900, (labelled as syntype, but it is probably not), SMF 118097/1; Assam, coll. Ehrmann ex coll. Schlüter, SMF 150113/1; Khasi Hills, figured in Godwin-Austen (1874), NHMUK 1903.7.1.757 (note that in the original sample it is erroneously 759) (11 specimens under the name affinis ); Khasi Hills, coll. W. Blanford, NHMUK 1906.1.1.743/2; Khasi Hills, India, Assam, NHMUK 1916.3.16.6-7/2; Khasi Hills, coll. Kennard, NHMUK 20150181/2 (mixed sample with Endothyrella plectostoma see NHMUK 20150180); Khasi Hills, NHMUK 20150196/2 (mixed sample with Endothyrella plectostoma ); Khasi Hills, Assam, ‘Preston’, V.W. MacAndrew Collection (Acc. No.1563), NHMUK 20150197/3; Khasi Hills, Bengal, 'Rolle, C/R June 03', V.W. MacAndrew Collection (Acc. No.1563), NHMUK 20150198/2; Khasi Hills, India, 'Rolle, C/R 8/5/13', V.W. MacAndrew Collection (Acc. No.1563), NHMUK 20150199/2.

Diagnosis.

A small, sinistral species with narrow umbilicus, conical dorsal surface with strong spiral lines, strongly, densely ribbed surface, and hairs standing in four rows on the body whorl; palatal plicae more or less straight, they are more or less divided; lamella slightly curved, with small denticles on the posterior side (they might fuse to the lamella), and a long upper plica on the anterior side of the lamella.

Measurements

(in mm): D: 10.1-10.4, H: 6.3-6.7 (n = 2, SMF 172073).

Differential diagnosis.

Endothyrella affinis has less shouldered whorls, wider umbilicus, weaker sculpture and it lacks the long horizontal plica anterior to the lamella. Endothyrella tricarinata differs from Endothyrella plectostoma by the larger size, more conical dorsal surface, narrower umbilicus, the shouldered whorls, the presence of only four rows of hairs, and the stronger sculpture. Endothyrella sowerbyi has much weaker dorsal sculpture and has wider umbilicus. See also Table 5.

Distribution.

All museum samples were collected from the Khasi Hills and Assam (Figure 11).

Remarks.

Two varieties of Plectopylis plectostoma have been described under the names Plectopylis plectostoma var. tricarinata and Plectopylis plectostoma var. exerta . Both of them differ from typical Endothyrella plectostoma specimens by the more shouldered whorls, and the more conical dorsal side of the shell having stronger spiral lines. No difference between the type specimens of these forms have been found except for the presence ( exerta ) and the absence ( tricarinata ) of hairs. The absence of hairs might be due to the corroded state of the syntypes of tricarinata . Although the difference between typical Endothyrella plectostoma and typical tricarinata / exerta shells seem to be minor, we found no intermediate forms, and in some cases we found mixed museum samples which indicate that the shells might have been collected from the same site. This suggest that Endothyrella plectostoma and Endothyrella tricarinata are distinct species.