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

description: Dadagulella conoidea (Verdcourt, 1996) comb. nov.
Figs 42, 84; Table 1
Gulella conoidea Verdcourt, 1996: 135-137, fig. 1.
Gulella conoidea – Tattersfield 1998b: 37. — Verdcourt 2006: 48.
Type material examined
TANZANIA: Holotype RMNH.MOL.57150: 1 ad., East Usambara foothills, Kwamgumi/Segoma Reserve, about 4.57°- 4.58°S, 38.43° - 38.45°E, near Muzi R./Sigi R. junction, leg. Frontier Tanzania (examined digital photograph only).
Other material examined
None.
Description
SHELL (Fig. 42). Large (5.5 mm high x 2.80 mm wide), of 8.0 whorls. Subconical (maximum width being in bottom third of the shell, at body whorl). Spire narrowly acuminate, almost cyrtoconoid (convex) rather than coeloconoid (spire angle 48°). Apex sharply pointed. Embryonic whorls “probably smooth but worn” (Verdcourt 1996). Later whorls with relatively weak ribs (about 11 per mm on penultimate whorl). Sutures relatively shallow. Umbilicus narrowly open. Peristome incomplete parietally, or nearly so. Dentition 3-fold (although could be interpreted as 4-fold), consisting of: one lamella-like parietal tooth, with a swelling above it that recalls that in D. rondoensis comb. nov.; one strongly bifid palatal tooth (or pair of teeth), not forming a parieto-palatal sinus; and a shallow columellar tooth or denticle. Shells and anatomy of juveniles unknown.
Range and habitat
Altitude and habitat not stated but probably in lowland forest at approximately 200 m at the type locality, northeastern Tanzania. Another species (D. radius comb. nov.) also occurs at Kwamgumi.
Remarks
See D. rondoensis comb. nov. above.
Key to species and subspecies (adult shells)
1. Dentition simple, 2-fold to 4-fold (Figs 35, 38, 41, 42, 51, 56, 62), never including a parietal denticle to the left of parietal tooth ............................................................................................................... 2
– Dentition complex, 5-fold to 8-fold (Figs 52-55, 57-61, 63, 64) (if in doubt key from here) ......... 8
2. Basal denticle absent ........................................................................................................................ 3
– Basal denticle present (may be partly or wholly hidden behind palatal tooth, e.g. Fig. 56, so if alternative fails return here) ............................................................................................................. 6
3. Shell small (up to 3.1 mm high) with very fine, very numerous ribs (about 27 per mm on penultimate whorl) (Fig. 37) ...................................................... D. meredithae (van Bruggen, 2000) comb. nov.
– Shell large (4.1 - 5.5 mm high) and with 13 or fewer ribs per mm on penultimate whorl (Figs 35, 41- 42) .................................................................................................................................................... 4
4. Shell ovate-acuminate (maximum width approximately at middle of shell); spire broadly acuminate (spire angle 56° or more); ribs sinuous (Fig. 35) ..................................................... D. delta sp. nov.
– Shell subconical (maximum width in bottom third of shell); spire narrowly acuminate (spire angle 52° or less); ribs not sinuous (Figs 41-42) ....................................................................................... 5
5. One palatal tooth, columellar dentition weak or absent; 4.10 mm high (Fig. 41) .............................. ...................................................................................... D. rondoensis (Verdcourt, 1994) comb. nov.
– Two palatal teeth; one strong shallow columellar tooth; 5.5 mm high (Fig. 42) ................................ ......................................................................................... D. conoidea (Verdcourt, 1996) comb. nov.
6. Deep-set columellar baffle clearly visible through aperture (if not so clearly visible, then apex pointed and not rounded) (e.g. Figs 51-57, 62-64) .......................................................................... 7
– Columellar baffle barely visible through aperture; apex rounded (Taita Hills, Kenya) (Fig. 33) ...... ............................................................................. D. nictitans (Rowson & Lange, 2007) comb. nov.
7. No columellar dentition other than deep-set baffle; basal denticle present, either completely hidden by a slab-like palatal tooth or visible only when shell is turned (Kimboza, Uluguru Mts, Tanzania) (Figs 28, 56) ..................................................................................................... D. ecclesiola sp. nov.
– Usually with shallow columellar dentition as well as deep-set baffle; basal denticle clearly visible in normal apertural view .................................................................................................................... 19
8. Parietal tooth strongly V-shaped, flaring, directed outwards; three palatal teeth; shell of 5.0 or fewer whorls (Figs 34, 61) .................................................................................... D. frontierarum sp. nov.
– Shell without this combination of characters ................................................................................... 9
9. Upper shallow columellar tooth strong, squarish, projecting into aperture as far or further than any deeper columellar baffle (Figs 30-31, 36, 58-59) .......................................................................... 10
– Shallow columellar dentition projecting less far into aperture than any deeper columellar baffle (Figs 51-57, 60-64) ................................................................................................................................. 12
10. Apex rounded; spire broadly acuminate, spire angle 70°; ribs weak, almost disappearing in the middle of the whorl (Virunga NP, DR Congo) (Fig. 36) .................................................................... .............................................................. D. selene (van Bruggen & Van Goethem, 1999) comb. nov.
– Apex sharply pointed; spire acuminate or coeloconoid, spire angle 65° or less; ribs prominent, running from suture to suture; apex finely radially striate in fresh specimens (Figs 30-31) .......... 11
11. Shell more than 4.0 mm high; parietal tooth simple, lamella-like; two palatal teeth (W. Usambara Mts, Tanzania) (Figs 31, 59) .......................................... D. cuspidata (Verdcourt, 1962) comb. nov.
– Shell up to 4.0 mm high; parietal tooth V-shaped; one palatal tooth (elsewhere in Tanzania) (Figs 30, 58) ..................................................................................................................... D. minareta sp. nov.
12. Outer palatal surface of aperture with very deep, long, furrow-like depression; basal denticle absent or not visible in apertural view (Figs 29, 33, 57) ........................................................................... 13
– Outer palatal surface of aperture with shallow, not furrow-like depression; basal denticle clearly visible in apertural view ................................................................................................................. 14
13. Apex sharply pointed; spire coeloconoid (Ngorongoro, Tanzania) (Figs 29, 57) .. D. cresswelli sp. nov.
– Apex rounded (Taita Hills, Kenya) (Fig. 33) ...... D. nictitans (Rowson & Lange, 2007) comb. nov.
14. Sculpture of widely-spaced, flaring, subtriangular, lamella-like ribs; spire narrowly acuminate (spire angle <50°) (Cabo Delgado, Mozambique) (Fig. 27) ......... D. delgada (Muratov, 2010) comb. nov.
– Shell without this combination of characters ................................................................................. 15
15. Shell 4.8 mm - 5.5 mm high (Pemba I., Tanzania) (Figs 32, 60) ..................... D. pembensis sp. nov.
– Shell up to 4.6 mm high ................................................................................................................. 16
16. Shell up to 3.3 mm high; parieto-palatal sinus narrow, appearing parallel-sided in apertural view; nearly always with an additional, small parietal denticle to the left of parietal lamella; nearly always with two basal denticles (Figs 21-26, 54-55) ... 17 (D. browni (van Bruggen, 1969) comb. nov. s.l.)
– Shell up to 4.6 mm high; parieto-palatal sinus wide, not parallel-sided in apertural view; always without a small parietal denticle to the left of parietal lamella, even if shell less than 3.3 mm high .............. 19
17. Only one basal denticle present; no columellar dentition other than a deep-set baffle (Mafia I., Tanzania) (Figs 21, 54) ................................................................... D. browni mafiensis subsp. nov.
– Two basal denticles almost always present; one or two columellar denticles present in addition to a deep-set baffle (Figs 22-26, 55) ..................................................................................................... 18
18. Shell 3.15 - 3.25 mm high; sutures relatively shallow; peristome complete; parieto-palatal sinus longer and narrower, not widening appreciably towards its inner end (Semuliki NP, Uganda) (Figs 22, 55; compare with Figs 23-26) ............................................ D. browni semulikiensis subsp. nov.
– Shell (2.55 - 3.20 mm high; sutures relatively deep; peristome incomplete parietally; parieto-palatal sinus shorter and broader, widening towards its inner end (South Africa, Mozambique, S. Tanzania) (Figs 23-26; compare with Figs 22, 55) ............ D. browni browni (van Bruggen, 1969) comb. nov.
19. Sculpture of numerous, fine ribs (15 or more per mm on penultimate whorl); spire coeloconoid, elongate (Mayotte) (Figs 40, 64) ............................................ D. minuscula mahorana subsp. nov.
– Shell without this combination of characters (e.g. Figs 1-20, 38-39) ............................................ 20
20. Shell 4.0 mm or more high, sculpture of few, coarse, widely-spaced ribs (5 - 10 per mm on penultimate whorl); dentition 4-fold to 5-fold (Taru Desert and elsewhere in SE Kenya) (Figs 6-8, 51). ............ ......................................................................... D. radius calva (Connolly, 1922) comb. et stat. nov.
– Shell without this combination of characters ................................................................................. 21
21. Dentition 5-fold or more, although when shallow columellar dentition is weak, might be considered 4-fold (lowlands of SE. Kenya and NE. Tanzania) (Figs 1-5, 9-20, 52-53) ....................................... ..................................................................................... D. radius radius (Preston, 1910) comb. nov.
– Dentition 4-fold, lacking a shallow columellar tooth (as in the lectotype) or 5-fold, with a shallow columellar tooth (as in the paralectotype) (Nzwani [Anjouan] I., Comoros) (Figs 38-39, 62-63) ..... ....................................................................... D. minuscula minuscula (Morelet, 1877) comb. nov.
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 32-34, DOI: 10.5852/ejt.2013.37, http://zenodo.org/record/3806770