Haploptychius blanfordi (Theobald, 1864)

Sian Man, Nem, Siriboon, Thanit, Lin, Aung, Sutcharit, Chirasak & Panha, Somsak, 2022, Revision of the carnivorous land snail family Streptaxidae (Stylommatophora, Achatinina) in Myanmar, with description of four new species, ZooKeys 1110, pp. 39-102 : 39

Haploptychius blanfordi (Theobald, 1864)

Fig. 10A-C

Streptaxis blanfordi Theobald, 1864: 245. Type locality: Montibus Arakanensibus provincia Pegu [Arakan Mountains in Bago Region, Myanmar]. Nevill 1878: 2.

Streptaxis birmanica Blanford, (in MSS.) Theobald, 1864: 245, 246 (in part). Type locality: Pegu [Bago Region, Myanmar]. Theobald 1865: 277.

Streptaxis blanfordianus Stoliczka 1871: 163, pl. 7, figs 8, 9 (unjustified emendation). Pfeiffer 1876: 494.

Streptaxis birmanica - Hanley and Theobald 1876: 4, pl. 8, fig. 5 (non Theobald 1864).

Streptaxis blanfordi var. - Godwin-Austen 1895: 443.

Haploptychius blanfordianus - Kobelt 1906: 143, 144, pl. 57, fig. 15, pl. 62, figs 4, 5.

Haploptychius blanfordi - Richardson 1988: 212.

Streptaxis blanfordi - Hanley and Theobald 1870: 4, pl. 8, fig. 10 (non Theobald 1864).

Streptaxis birmanicus [sic] - Richardson 1988: 251.

Material examined.

Syntype NHMUK 1888.12.4.777-779 (3 shells; Fig. 10A ) from Pegu. NHMUK 1909.3.15.71 (1 shell; Fig. 10C ) ex. Godwin-Austen collection. Pegu, Arakan: NHMUK 1909.3.15.93 (3 shells) ex. H. Blanford collection. Akouktoung, Pegu: NHMUK 1906.2.2.338 (4 shells; Fig. 10B ) ex. W.T. Blanford collection. Pegu, Arakan: NHMUK 1909.3.15.93 (3 shells) ex. H. Blanford collection.

Diagnosis.

Haploptychius fischeri (Morlet, 1887) almost shares the same shell form as H. blanfordi , but the latter possesses a more depressed shell, penultimate whorl more bulging, aperture wider, longer and subquadrangular shape.

Description.

Shell oblique-heliciform, white, and translucent; whorls 6; spire convex with distinct suture. Shell surface glossy with fine transverse ridges that diminish below periphery. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery rounded; last whorl axially deflected. Aperture semi-ovate; peristome discontinuous, thickened, expanded, and reflected. Apertural dentition with one strong parietal and small palatal lamellae. Umbilicus open and deep (Fig. 10A-C ).

Distribution.

This species has been recorded with a wide distribution range from Arakan [Rakhine State], Pegu [Bago Region], and Shan State in Myanmar. However, the record from Cocos Islands in the southern Indian Ocean by Blanford and Godwin-Austen (1908) needs to be verified with modern evidence rather than by shell morphology alone.

Remarks.

The taxonomic status of this species is still ambiguous because it is identical in shell morphology to Streptaxis birmanica . Theobald (1864) consecutively described Streptaxis blanfordi and Streptaxis birmanica based on specimens from the same geographical area as Pegu. These two nominal species resemble each other in having one parietal and one palatal lamella, whereas they differ in only minor characters of shell shape and size. In this revision, we consider these two nominal species as synonyms. Only the type specimens of H. blanfordi could be located and examined; we therefore consider Streptaxis birmanica as the junior synonym.

The original spelling of the species was Haploptychius blanfordi , which was intentionally modified to Haploptychius blanfordianus by Stoliczka (1871) but for an unclear reason. This subsequent spelling of Haploptychius blanfordianus is an unjustified emendation made available with its own authorship and date, and so became a junior objective synonym (ICZN 1999: Arts 32.3, 33.2.3, 50.5).

Theobald (1864) clearly stated that Streptaxis birmanica W. Blanford, (in MSS.) was described based on a single specimen received from W.T. Blanford. However, we could not locate this single shell as the holotype fixed by monotypy. Theobald (1864) also stated that the other two shells lacked the palatal lamella and were of a relatively smaller size, which are recognized as distinct varietal entities. Therefore, these two specimens are excluded from the type series of Streptaxis birmanica . The authorship was originally attributed to W.T. Blanford as the manuscript name. However, since Blanford did not write the description or credit the description to W.T. Blanford, the taxon is attributed to Theobald only (ICZN 1999: Art. 50.1.1).

Figures

Figure 10. A-C Haploptychius blanfordi A syntype NHMUK 1888.12.4.777 - 779 from Pegu with apertural dentition B specimen NHMUK 1906.2.2.338 from Akouktoung, Pegu C specimen NHMUK 1909.3.15.71 from Pegu D Haploptychius burmanicus, syntype NHMUK 1906.2.2.199 from Tongoop, Arakan with apertural dentition.