Dadagulella minuscula minuscula ( Morelet, 1877 ) minuscula (Morelet, 1877

Rowson, Ben & Tattersfield, Peter, 2013, Revision of Dadagulella gen. nov., the “ Gulella radius group ” (Gastropoda: Streptaxidae) of the eastern Afrotropics, including six new species and three new subspecies, European Journal of Taxonomy 37, pp. 1-46 : 27-28

publication ID

https://doi.org/ 10.5852/ejt.2013.37

publication LSID

lsid:zoobank.org:pub:ADF6394E-77B5-4309-87FE-4097FDE0A3FD

DOI

https://doi.org/10.5281/zenodo.3815767

persistent identifier

https://treatment.plazi.org/id/4511E41D-D83E-FFDC-FE00-FD63F6D1F80C

treatment provided by

Carolina

scientific name

Dadagulella minuscula minuscula ( Morelet, 1877 )
status

comb. nov.

Dadagulella minuscula minuscula ( Morelet, 1877) View in CoL comb. nov. Figs 38-39 View Figs 36-40 , 62-63 View Figs 51-64 , 84 View Fig ; Table 1 View Table 1

Pupa minuscula Morelet, 1877: 340 View in CoL .

Pupa fischeriana Morelet, 1877 : pl. XII, fig. 5 (objective synonym).

Ennea fischeriana – Morelet 1881: 230-231. — Richardson 1988: 103 (objective synonym).

Ennea (Gulella) fischeriana – Tryon 1885: 100, pl. 20, fig. 39.

Ennea (Uniplicaria) fischeriana – Kobelt 1905: 166, pl. 22, fig. 10; 1910: 158.

Pupa minuscula View in CoL – Kobelt 1905: 166; 1910: 158. — van Bruggen 1975: 166.

Ennea minuscula – Preston 1910: 529.

Gulella minuscula Morelet View in CoL (non Gulella minuscula Emberton & Pearce, 2000 View in CoL ) – Fischer-Piette & Vukadinovic 1974: 55. — Richardson 1988: 103. — Rowson 2007a: 441-442. — Rowson & Lange 2007: 31. — Muratov 2010: 277.

Type material examined

COMOROS: lectotype (here designated) and paralectotype NHMUK.1893.2.4.87-88: 2 ads, “ Anjouan I.” (Nzwani I., approx. 12.22°S, 44.45°E), labelled “ types ”. The smaller of the two specimens is apparently the shell figured in Morelet   GoogleMaps (1877: pl. XII, fig. 5) under the name “ fischeriana ”. It   GoogleMaps was evidently formerly on a white card mount. This   GoogleMaps shell is here designated lectotype, while the larger is considered a paralectotype (although Morelet’s description could in fact have been made from a single shell).

Type locality

“Dans l’île d’Anjouan (Johanna)” ( Morelet 1877; from title of paper).

Description

SHELL ( Figs 38-39 View Figs 36-40 , 62-63 View Figs 51-64 ). Variable in size, shape and dentition, small to large (3.00 - 4.10 mm high x 1.90 - 2.00 mm wide), of 6.5 - 7.0 whorls. Ovate-acuminate, spire broadly acuminate (spire angle 48 - 63°). Apex pointed. Embryonic whorls smoothly granulate. Later whorls with relatively fine, numerous ribs (10 - 13 per mm on penultimate whorl). Sutures relatively deep. Umbilicus closed or nearly so. Peristome complete, or incomplete parietally. Outer palatal surface of aperture with a depression corresponding to the palatal tooth. Dentition 4-fold (lectotype, Figs 38 View Figs 36-40 , 62 View Figs 51-64 ) to 5-fold (paralectotype, Figs 39 View Figs 36-40 , 63 View Figs 51-64 ), consisting of: one lamella-like parietal tooth; one slab-like palatal tooth, often bifid, but with parietopalatal sinus barely present; one basal denticle; and one deep-set columellar baffle, always visible. An additional shallow columellar denticle is present in the paralectotype. Shells and anatomy of juveniles unknown.

Range and habitat

Nzwani (Anjouan) island in the Comoros archipelago; habitat unknown.

Remarks

Morelet (1877) described this species from Anjouan (type locality implied by the paper’s title) under the name “ Pupa minuscula ” but figured it under the name “ Pupa fischeriana ” (pl. XII, fig. 5). In the paper he compared it to three species from “Île Bourbon” (Réunion), but none is very like it, suggesting Morelet was unaware of other Dadagulella gen. nov. species and probably meaning that D. m. minuscula comb. nov. was the first species of the group to be collected. Two of the Réunion species are streptaxids of the Mascarene genus Gonospira Swainson, 1840 while the third belongs to the Pupillidae Turton, 1831 (see Griffiths & Florens 2006). Although Kobelt (1905, 1910) classified D. m. minuscula comb. nov. (under fischeriana ) in the subgenus Ennea (Uniplicaria) L. Pfeiffer, 1856 , it is very unlike Pupa cerea Dunker, 1848 , the type species of Uniplicaria. Preston (1910) made a more relevant comparison in his description of Ennea radius , noting that his species had coarser ribs, a columellar denticle, and a bifid palatal tooth that were absent in D. m. minuscula comb. nov. Given these remarks and the fact that Preston cited only Anjouan as a locality for D. m. minuscula comb. nov., it thus appears he examined only the lectotype of the latter or material that was very like it. We agree that these features distinguish the lectotype of D. m. minuscula comb. nov. from that of D. r. radius comb. nov. However, the paralectotype (if it is such; see also below) of D. m. minuscula comb. nov., while having similarly fine ribs, has a stronger shallow columellar denticle that resembles that of D. r. radius comb. nov. Although we have seen no mainland specimen that exactly matches either of them, both specimens of D. m. minuscula comb. nov. fall within the range of variation seen in D. r. radius comb. nov. in other respects. It is therefore possible that the two taxa are synonymous, in which case Morelet’s name would take priority over Preston’s. It is even possible that D. minuscula comb. nov. s.l. consists of populations of D. radius comb. nov. s.l. derived from specimens introduced from the African mainland (the alternative, that D. radius comb. nov. s.l. was introduced into East Africa from the Comoros appears unlikely given the variation seen in East African populations and the many similar species there). That said, the isolated, volcanic Comoros archipelago comprises a region of endemism in itself and D. minuscula comb. nov. s.l. could easily be a Comoros endemic whose overlapping variation with D. radius comb. nov. s.l. is due to homoplasy. Resolving the relationships between these two taxa, and D. m. mahorana subsp. nov. below, is likely to require anatomical or molecular data. Until such information becomes available, and while we focus on other issues within Dadagulella gen. nov., we maintain the two species as separate. Van Bruggen (1986) took a similar approach with two other streptaxids, one described by Preston from the Shimba Hills, the other by Morelet from Mayotte.

There is a nomenclatural issue concerning the name minuscula Morelet, 1877 . Morelet (1881) tried to replace the name used for the (1877) description, Pupa minuscula , with the name used for the (1877) figure, Ennea fischeriana . Morelet (1881) wrote that the name P. minuscula had been published in error. Subsequently both Tryon (1885: 100) and Kobelt (1905: 166; 1910: 158) accepted fischeriana as the species name. However, when revising the fauna of the Comoros, Fischer-Piette & Vukadinovic (1974) disagreed. They treated E. fischeriana is an objective synonym of P. minuscula since the latter was not preoccupied and was validly introduced. This point of view was followed by Richardson (1988). As a consequence, the lectotype of D. m. minuscula comb. nov. in NHMUK also becomes the lectotype of E. fischeriana and the latter name remains unavailable for a taxon founded on another specimen. This includes the paralectotype, which is further discussed below.

Finally, we note that, although Emberton & Pearce (2000) described a junior homonym of minuscula Morelet, 1877 in Gulella ( G. minuscula Emberton & Pearce, 2000 ) no replacement name is required since minuscula Morelet is here transferred from Gulella to Dadagulella gen. nov.

NHMUK

NHMUK

NHMUK

Natural History Museum, London

Kingdom

Animalia

Phylum

Mollusca

Class

Gastropoda

Order

Stylommatophora

Family

Streptaxidae

Genus

Dadagulella

Loc

Dadagulella minuscula minuscula ( Morelet, 1877 )

Rowson, Ben & Tattersfield, Peter 2013
2013
Loc

Gulella minuscula

Muratov I. V. 2010: 277
Rowson B. 2007: 441
Rowson B. & Lange C. N. 2007: 31
Richardson C. L. 1988: 103
Fischer-Piette E. & Vukadinovic D. 1974: 55
1974
Loc

Ennea minuscula

Preston H. B. 1910: 529
1910
Loc

Ennea (Uniplicaria) fischeriana

Kobelt W. 1905: 166
1905
Loc

Pupa minuscula

Bruggen A. C. van 1975: 166
Kobelt W. 1910: 158
Kobelt W. 1905: 166
1905
Loc

Ennea (Gulella) fischeriana

Tryon G. W. 1885: 100
1885
Loc

Ennea fischeriana

Richardson C. L. 1988: 103
Morelet A. 1881: 230
1881
Loc

Pupa minuscula

Morelet A. 1877: 340
1877
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