Dadagulella cresswelli, Rowson & Tattersfield, 2013

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 : 18

Dadagulella cresswelli sp. nov.

urn:lsid:zoobank.org:act:B3362D6F-2118-4D1D-8B25-098E25B0C3B2

Figs 29 , 57 , 84 ; Table 1

Etymology

After Pete Cresswell, who collected the specimen.

Type material examined

TANZANIA: holotype NMW.Z.2012.042.00001 : 1 ad., Ngorongoro Crater, Arusha Region, crater rim on southeastern side, heavy rainforest leaf litter, leg. P.L. Cresswell, 2 Jun.1996.

Other material examined

None.

Description

SHELL ( Figs 29 , 57 ). Medium-sized (3.70 mm high x 1.80 mm wide), of 7.0 whorls. Ovate-acuminate, spire coeloconoid (spire angle 52°). Apex sharply pointed. Embryonic whorls smoothly granulate. Later whorls with relatively fine ribs (13 per mm on penultimate whorl). Sutures shallow. Umbilicus narrowly open. Peristome complete. Outer palatal surface of aperture with a very deep, long, furrow-like depression corresponding to the palatal tooth. Dentition 5-fold, consisting of: one V-shaped parietal tooth; one bifid slab-like palatal tooth, forming a clear parieto-palatal sinus, with the upper cusp projecting into the sinus; a deep-set columellar baffle and two shallower columellar denticles. Shells and anatomy of juveniles unknown.

Range and habitat

Forest at the type locality in northern Tanzania. The vegetation is presumably of a montane type, since the crater floor is above 1700 m while the rim rises to over 2400 m or higher.

Remarks

This species is distinctive in its deep, long furrow on the outer palatal surface in combination with the coeloconoid spire and dentition. D. minerata sp. nov. shares these features, but differs in having weaker ribs and less complex dentition. It is the only Dadagulella gen. nov. species thus far collected in the volcanic (as opposed to block-faulted) highlands of Tanzania or Kenya.

Figures

Figs 27-35. Adult shells of Dadagulella gen. nov. species. 27. D. delgada (Muratov, 2010) comb. nov., syntype, Cabo Delgado (after Muratov 2010). 28. D. ecclesiola sp. nov., holotype, Kimboza. 29. D. cresswelli sp. nov., holotype, Ngorongoro. 30. D. minareta sp. nov., holotype, Kimboza. 31. D. cuspidata (Verdcourt, 1962) comb. nov., holotype, Shume. 32. D. pembensis sp. nov., holotype, Ngezi. 33. D. nictitans (Rowson & Lange, 2007) comb. nov., holotype, Macha. 34. D. frontierarum sp. nov., holotype, Mtai. 35. D. delta sp. nov., holotype, Mwanihana.

Figs 51-64. Apertures of adult shells of Dadagulella gen. nov. species (not to scale). 51. D. radius calva, lectotype, Taru Desert. 52. D. radius radius, lectotype, Shimba Hills. 53. D. radius radius, Amboni. 54. D. browni mafiensis subsp. nov., holotype, Mlula. 55. D. browni semulikiensis subsp. nov., holotype, Semuliki NP. 56. D. ecclesiola sp. nov., holotype, Kimboza (two views of shell showing basal tooth only visible when shell angled). 57. D. cresswelli sp. nov., holotype, Ngorongoro. 58. D. minareta sp. nov., holotype, Kimboza. 59. D. cuspidata comb. nov., holotype, Shume (note shell angled slightly differently to that in Fig. 31). 60. D. pembensis sp. nov., holotype, Ngezi. 61. D. frontierarum sp. nov., holotype, Mtai. 62. D. minuscula minuscula, lectotype, Nzwani. 63. D. minuscula minuscula, paralectotype, Nzwani. 64. D. minuscula mahorana subsp. nov., holotype, Mayotte.

Fig. 84. Distribution of Dadagulella gen. nov. species, based on published records and material examined here (for additional records of D. meredithae comb. nov. in northern Malawi see van Bruggen 2000). The inset on the left corresponds to the map on the right.