Dadagulella pembensis Rowson & Tattersfield 2013, sp. nov.
Creators: name: Rowson, Ben
name: Tattersfield, Peter
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Stylommatophora
Streptaxidae
Dadagulella
Dadagulella pembensis

description: Dadagulella pembensis sp. nov.
urn:lsid:zoobank.org:act: 4442210F-A097-400D-B34F-96A4B7677CE7
Figs 32, 46, 60, 66-68, 70, 75, 79-80, 84; Table 1
““ Gulella” radius (Preston, 1910) ” – Rowson et al. 2010 b: 9-10, 28-29, figs 60-61.
Etymology
From Pemba Island, with the final ‘a’ elided for euphony.
Type material examined
TANZANIA: holotype NMW.Z.2009.013.00227: 1 ad., Ngezi Forest Reserve (4.94°S, 39.69°E), Pemba I., Zanzibar, dry forest on dark, sandy soil on coral rag on Tondooni peninsula within reserve, leg. BR, B. H. Warren & CFN, 7 Feb. 2009; fig. 60 in Rowson et al. (2010b). Paratypes NMW. Z. 2009.013.00228: 2 ads, data as holotype. Paratypes MRAC. MT. 803796-7: 2 ads, data as holotype. Paratypes NHMUK. 20120261: 2 ads, data as holotype. Paratypes NMK: 2 ads, data as holotype. Paratypes NMT: 2 ads, data as holotype. Paratypes NMSA. L8694/T3063: 2 ads, data as holotype. Paratypes RMNH. MOL. 288090: 2 ads, data as holotype.
Other material examined
TANZANIA: NMW. Z.2009.013.00229: 15 juvs, data as holotype; one figured as fig. 61 in Rowson et al. (2010 b). NMW. Z.2009.013.00230: 3 ads, near Chwaka (5.39° S, 39.77° E), Pemba I., Zanzibar, clove and fruit tree woodland on dark, sandy soil, leg. BR, B. H. Warren & CFN, 15 Feb. 2009. NMW. Z.2009.013.00231: 3 ads, Msitu Mkuu Forest Reserve (5.00° S, 39.83° E), Pemba I., Zanzibar, moist forest on dark (not sandy) soil on coral rag in high forest in north of reserve, leg. BR, B. H. Warren & CFN, 10 Feb. 2009. NMW. Z.2009.013.00232: 3 ads, Ngezi Forest Reserve, Pemba I., Zanzibar, dry forest and thicket on dark, sandy soil on coral rag on coast of Tondooni peninsula within reserve, leg. BR, B. H. Warren & CFN, 8 Feb. 2009. NMW. Z.2009.013: Many additional ads and juvs from the type locality and other sites on Pemba I., Feb. 2009; see table 2 of Rowson et al. (2010 b).
Description
SHELL (Figs 32, 46, 60). Large (4.80 - 5.50 mm high x 2.00 - 2.50 mm wide), of 6.5 - 7.5 whorls. Ovateacuminate, spire narrowly to broadly acuminate (spire angle 51 - 65°). Apex sharply pointed. Embryonic whorls smoothly granulate. Later whorls with relatively coarse ribs (12 - 15 per mm on penultimate whorl). Sutures shallow, shell appearing relatively straight-sided. Umbilicus closed or nearly so. Peristome complete, or incomplete parietally. Outer palatal surface of aperture with a depression corresponding to the palatal tooth and often another corresponding to the basal tooth. Dentition 6-fold, consisting of: one lamella-like parietal tooth; one slab-like palatal tooth, forming a parieto-palatal sinus; one basal denticle; a deep-set columellar baffle, sometimes folded, sub-bifid or sub-trifid; and two shallower, broad columellar denticles. Juvenile shells (Fig. 46) with 3-fold dentition, similar to some forms of D. r. radius comb. nov.: one parietal lamella; one basal tooth; and one columellar thickening. Earlier basal teeth are retained in juveniles.
CEPHALOPODIUM. Pale yellow, with apricot to orange tentacle retractors.
SALIVARY GLANDS (Fig. 70). United, soft, not tumid, elongate, Y-shaped; each duct leaving at the apex of the lobe and evenly thick throughout.
RADULA (Figs 66-68). With a unicuspid central tooth and around 15 laterals in each half-row, gradually diminishing in size laterally. All laterals bicuspid, tricuspid, or quadricuspid, with outer cusps much smaller than inner cusps. Teeth delicate, short and flake-like at the ventral end of the radular ribbon.
GENITALIA (Figs 75, 79, 80). Vas deferens appearing thickened prior to insertion on penis, but actually with a short, broad parallel diverticulum. Penial sheath absent but with a thin sheath-like layer contiguous with wall of lower penis. Interior of penis with weak radial pilasters and small rhombic pads. Apical, muscular part of penis with a single large hook, associated with a spatulate “scoop” with microscopically serrated tip. Elsewhere in penis, one or two longitudinal rows of short, simple hooks mounted on rhombic pads. “Spermatophore” (see Discussion) present in penis of two Ngezi specimens; partially digested remains in bursa of another.
Range and habitat
Pemba Island, Tanzania, where widespread in forest and other vegetated habitats.
Remarks
This species was discussed by Rowson et al. (2010 b), who suggested a thorough revision of the group to establish whether the Pemba populations were part of a variable D. radius comb. nov. or a subspecies or species endemic to Pemba. This uncertainty was incorporated into their conclusions on endemism on the island (Rowson et al. 2010 b: 28-29, 32). We find here that there is little or no overlap with D. radius comb. nov. s.l. or other species, so conclude that this is an island endemic, which we here name D. pembensis sp. nov. Like specimens of D. r. radius comb. nov. on the opposite mainland at Amboni (e.g. Figs 15, 53), D. pembensis sp. nov. is large and has a complex pattern of 6-fold dentition. However it is distinguishable from them by its even larger size, shallower sutures, and having on average an extra 0.5 whorls. It differs from D. minuscula mahorana subsp. nov. which has similar dentition, in its larger size, shallower sutures, and stronger and more widely spaced ribs.
description: Published as part of 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, pp. 1-46 in European Journal of Taxonomy 37 (37) on pages 20-22, DOI: 10.5852/ejt.2013.37, http://zenodo.org/record/3806770