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

description: Genus Dadagulella gen. nov.
urn:lsid:zoobank.org:act: 1C3959C3-50E5-4DFF-A5AC-67BB9F05A042
Figs 1-84; Table 1
Type species
Ennea radius Preston, 1910.
Included species
Sixteen. In addition, D. radius (Preston, 1910) comb. nov. and D. minuscula (Morelet,1877) comb. nov. are treated as having two subspecies and D. browni (van Bruggen, 1969) comb. nov. as having three (see below).
Diagnosis
Shell small (2.3 - 5.5 mm high), ovate to ovate-acuminate with an acuminate (sometimes coeloconoid or cyrtoconoid) spire; strongly and often sinuously radially ribbed, never smooth. Peristome reflected. Aperture dentate, with at least one parietal and one palatal tooth. Juvenile aperture (known from 7-8 species) dentate (except possibly in D. nictitans comb. nov.), aperture not downturned. Radula (known from three species) bearing multicuspid teeth, the outer cusps much smaller than the inner. Other anatomy (known from six species): salivary gland bilobed or Y-shaped. Vas deferens thickened or with diverticulum prior to insertion on penis, penis lacking sheath, with a muscular apex in which is embedded a spatulate scoop with a microscopically serrated tip, usually associated with one or two large apical hooks, and a few (<40) smaller hooks lower down. For dimensions, see Table 1.
Etymology
Prefix from Swahili noun “ dada ” meaning sister, with reference to the apparent relationships and East African centre of diversity of the group.
Description
SHELL (Figs 1-64). Small to medium-sized relative to species of Gulella (2.3 - 5.5 mm high x 1.4 - 2.8 mm wide), of 4.5 - 8 whorls. Ovate to ovate-acuminate (maximum width being approximately at middle of shell, usually at penultimate whorl) or subconical (maximum width being in bottom third of the shell, at body whorl). Spire characteristically narrowly to broadly acuminate, occasionally coeloconoid or cyrtoconoid (spire angle 43-77°), angle varying a little within most species. Apex (i.e. top of spire) pointed in most species, but rounded in others. Sutures usually deep, shells never completely smoothsided. Umbilicus closed or narrowly open, this sometimes varying within a species. Embryonic whorls usually smoothly granulate, with fine radial striae in two species, or irregularly punctate in another. The last part of the embryonic shell is sculptured with very fine radial striae in most (possibly all) species but these are worn away in all but the freshest individuals. Later whorls never smooth, with radial ribs (5 - 27 per mm on penultimate whorl) running from suture to suture, often strong and/or sinuous, lamella-like in some species. Peristome complete, or incomplete parietally, always reflected to some extent. Outer palatal surface of aperture with a depression, sometimes furrow-like, corresponding to the palatal tooth, and sometimes another corresponding to the basal tooth. Dentition 3-fold (rarely, and debatably, 2-fold) to 8-fold. Dentition consisting of at least one parietal tooth and one palatal tooth, the latter often slablike and/or bifid, sometimes forming a parieto-palatal sinus. Usually also with one deep-set columellar baffle, folded or sub-bifid or sub-trifid in some species. Often with additional parietal, palatal, basal and/or columellar teeth or denticles. Dentition is variable in some species but the form, as well as the number, of the teeth is often consistent enough to distinguish species. Juvenile shells (known from 7-8 species) always with 3-fold to 4-fold apertural dentition (Figs 43-50) except in one species, D. nictitans comb. nov., where the only known juvenile has no teeth. In several species, some or all of the teeth in juvenile shells appear to be resorbed at intervals.
CEPHALOPODIUM. Pale cream or yellow, usually with apricot-coloured to orange tentacle retractors and sometimes with brown speckles on the mantle.
PALLIAL COMPLEX. Sigmurethrous, with long zone of contact between long, oblong kidney and hindgut, pulmonary cavity not strongly vascularised.
SALIVARY GLANDS (Figs 69-72). United, soft, not tumid, elongate, bilobed to Y-shaped; each duct leaving at the apex of the lobe and evenly thick throughout.
BUCCAL MASS. Very small and elongate, radula correspondingly small, tightly enrolled and difficult to locate or prepare.
RADULA (Figs 65-68). (known from three species) With a unicuspid central tooth and 9 - 15 laterals in each half-row, diminishing gradually in size laterally. Most or all laterals distinctively bicuspid or multicuspid, with outer cusps smaller or much smaller than inner cusps. Teeth are somewhat delicate (or flexible; Aiken 1981) and are short and flake-like at the ventral end of the radular ribbon.
GENITALIA. (Figs 73-83) (known from six species) Hermaphroditic duct diverticulum (talon) short, large, sausage-shaped, not convoluted. Bursa copulatrix attending albumen gland. Acini of prostate indistinct to distinct. Vagina attenuate. Oviduct often containing a single large egg. Vas deferens either thickened prior to insertion on penis, or appearing as such but actually with a diverticulum lying parallel to it. Vas deferens entering penis subapically. Penial retractor muscle branching off columellar muscle, attaching partly to vas deferens, thus sometimes bifid or nearly so. Penis elongate, tubular. Penial sheath absent, but lower part sometimes surrounded by a thin sheath-like layer contiguous with walls of lower penis. Interior of penis with weak radial pilasters and small rhombic pads, sometimes with a longitudinal pilaster or short rounded lobe. Apical part of penis with a spatulate or broad “scoop”. One end with a microscopically serrated tip, the other end deeply embedded in muscular apex of penis. Scoop usually associated with one or two large, broad hooks, lying just behind or underneath it. Scoop and hook(s) could conceivably act together as a grip or pincer. Elsewhere in penis, a longitudinal row or group of few (<40) short, simple hooks mounted on rhombic pads. “Spermatophore” (see Discussion) detected in two species: comma-shaped, lying with reservoir in vagina with longitudinally ribbed tail extending into mid penis. End of tail probably originally weakly attached to wall of penis [as in one specimen of D. radius radius (Preston, 1910) comb. nov.] but subsequently detached. Partially digested tail fragments present in bursa of one specimen of D. pembensis sp. nov.
Known distribution
Eastern Kenya, eastern Tanzania, western Uganda, eastern DR Congo, Malawi, eastern Zambia, Mozambique, north-eastern South Africa, Comoros archipelago (Fig. 84).
Gender
Feminine.
Comparison and remarks
See General Discussion.
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 3-6, DOI: 10.5852/ejt.2013.37, http://zenodo.org/record/3806770