Endothyrella robustistriata Pall-Gergely

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 : 41

Taxon classification Animalia Pulmonata Plectopylidae

Endothyrella robustistriata Pall-Gergely sp. n. Figures 9 K–L, 23 C–D

Endothyrella robustistriata 1914b Plectopylis (Endothyra) minor (partim), - Gude: The Fauna of British India …: 76.

Type material.

Munipur, Laisen Peak, coll. Godwin-Austen, NHMUK 1903.7.1.3453/1 (holotype, Figure 23D); Naga Hills, Ihang valley, coll. Godwin-Austen, NHMUK 1903.7.1.770/3 paratypes; Naga Hills, coll. Godwin-Austen, NHMUK 1903.7.1.767/3 paratypes (Figure 23C); Lhota Naga Hills, coll. Chennell, NHMUK 1903.7.1.765/4 paratypes.

Diagnosis.

A tiny species with elevated spire, smooth ventral side and strongly reticulated dorsal surface; parietal wall with a single lamella, an upper and a lower denticle posteriorly, and a long lower plica which reaches the peristome.

Description.

Shell tiny, sinistral, with slightly elevated spire and conical/domed dorsal surface; colour light brown, greenish or yellowish; protoconch consists of approx. 2 whorls, glossy, in some populations (NHMUK 1903.7.1.767, NHMUK 1903.7.1.770, NHMUK 1903.7.1.3453) only the last half whorl has a somewhat ribbed surface, whereas in another population (NHMUK 1903.7.1.765) nearly the whole protoconch is ribbed; dorsal surface of the teleoconch with clearly visible reticulated sculpture dominated by spiral lines; ventral side hairless, smooth, glossy, sometimes with radial growth lines; the ventral and dorsal surface change relatively abruptly above the middle line of the body whorls (from apertural = frontal view); inside the umbilicus there are sharp periostracal folds corresponding with radial ribs; whorls 4.5-4.75 (n = 3), slowly growing, separated by relatively deep suture; umbilicus narrow and deep; apertural lip whitish, thickened, normally not reflexed, or reflexed only near the umbilicus; callus very weak, nearly invisible in case of fresh shells, in case of old, corroded shells it becomes white; aperture without entering fold.

Two opened specimens were observed (NHMUK 1903.7.1.767 and NHMUK 1903.7.1.765). Parietal wall with one rather straight lamella which bends anteriorly; it has both the upper and lower ends elongated anteriorly; two small denticles visible at the posterior side of the lamella, one above and one below; lower plica very long, reaches the peristome; palatal wall with six plicae; first slim and short, the second–fifth plicae horizontal; they do not seem to be divided if we observe through the translucent shell wall, but their middle portion (where the lamella is present on the parietal wall) is much lower; the posterior ends of the middle plicae slightly bent downwards, whereas the anterior parts are straight and horizontal; the last plica is short and slightly curved (Figure 9 K–L).

Measurements

(in mm): D: 4.1-4.6, H: 2.3-3.5 (n = 2 NHMUK 1903.7.1.765).

Differential diagnosis.

Endothyrella blanda is similar in shell shape to Endothyrella robustistriata sp. n., but is larger, has hairy ventral surface (or if hairs are missing, than hollows are visible indicating the hairs’ positions), and on its dorsal surface the radial lines are dominant. See also under Endothyrella macromphalus and Endothyrella williamsoni and Table 5.

Etymology.

The word robustistriata means strongly striated (Latin) which refers to the prominent spiral striae of the new species on the dorsal side of its shell.

Type locality.

Munipur, Laisen Peak.

Distribution.

The new species is known only from the Naga Hills and Manipur (Figure 11).