Revision of Dadagulella gen. nov., the “ Gulella radius group ” (Gastropoda: Streptaxidae) of the eastern Afrotropics, including six new species and three new subspecies
Author
Rowson, Ben
05D46259-DA45-45A4-9127-5AF361D566A7
Biodiversity & Systematic Biology, National Museum of Wales, Cathays Park, Cardiff, UK CF 10 3 NP. Email: ben. rowson @ museumwales. ac. uk & urn: lsid: zoobank. org: author: 05 D 46259 - DA 45 - 45 A 4 - 9127 - 5 AF 361 D 566 A 7
Author
Tattersfield, Peter
8C55642E-B18A-461B-9BF9-31CB6DB7A070
Biodiversity & Systematic Biology, National Museum of Wales, Cathays Park, Cardiff, UK CF 10 3 NP. Email: ben. rowson @ museumwales. ac. uk & urn: lsid: zoobank. org: author: 8 C 55642 E-B 18 A- 461 B- 9 BF 9 - 31 CB 6 DB 7 A 070
text
European Journal of Taxonomy
2013
2013-02-04
37
1
46
journal article
22334
10.5852/ejt.2013.37
9682b45b-5e22-4965-a293-e203660e0ed3
2118-9773
3806770
ADF6394E-77B5-4309-87FE-4097FDE0A3FD
Dadagulella radius calva
(
Connolly, 1922
)
comb. et stat. nov.
Figs 6-8
,
51
,
84
;
Table 1
Gulella calva
Connolly, 1922: 495
, pl. XIV, fig. 35.
Gulella calva
–
Verdcourt 1962: 17
;
1983: 234
. —
Richardson 1988: 62
. —
Verdcourt 2000: 215
;
2006: 49
.? “
Gulella radius
(Preston)
var. (K, Mrima Hill Forest)”
–
Verdcourt 1962: 22
.
Type material examined
KENYA
:
lectotype
(here designated)
NHMUK
.1937.12.30.486:
1 ad.
, Taru Desert (i.e. a semi-arid area of southeastern Kenya now partly in the Tsavo East National Park, approx.
3.40°S
,
39.00°E
), leg. Percival, labelled “type”, and apparently the shell figured in
Connolly (1922
: pl. XIV, fig. 35).
Figs 6-26.
Adult shells of
Dadagulella radius
(
Preston, 1910
)
comb. nov.
,
D. browni
(van
Bruggen, 1969
)
comb. nov.
and their respective subspecies.
6-20.
D. radius
comb. nov.
s.l.
6-8.
D. radius
calva
(
Connolly, 1922
)
:
6.
Lectotype, Taru Desert.
7.
Taru Desert near Malindi.
8.
Near Mombasa.
9-20.
D. radius radius
:
11.
Lectotype, Shimba Hills.
12.
Gazi.
13.
also Gazi.
14.
Diani Beach.
15.
Amboni.
16.
Kimboza.
17.
Mkungwe.
18.
Pugu.
19.
Mbudya I.
20.
Jozani.
21-26.
D. browni
comb. nov.
s.l.
:
21.
D. browni mafiensis
subsp. nov., holotype, Mlula.
22.
D. browni semulikiensis
subsp. nov., holotype, Semuliki NP.
23-26.
D. browni browni
:
23.
Mwanihana.
24.
Mzelezi.
25.
Pomene Bay.
26.
Holotype, Lake Sibayi (after van
Bruggen 1969
).
Other material examined
KENYA
:
NMW
.1955.158.25052: 5 ads, “ca. lat. 3°5’, long. 39°27’”, standing as “
calva
Co.
” and later labelled “
cf.
radius
” by B. Verdcourt. Assuming that the latitude refers to a point south rather than north of the equator, the coordinates correspond to a point in the Taru Desert, ±
75 km
inland of Malindi.
RMNH
.MOL.288087:
1 ad.
, near
Mombasa
(approx.
4.04°S
,
39.66°E
), amongst river debris,
Sep. 1987
.
Description
SHELL (
Figs 6-8
,
51
). Large (4.00
-
4.60 mm
high x
2.10
-
2.50 mm
wide), of 6.5
-
8.0 whorls. Ovateacuminate, but more columnar than other
Dadagulella
gen. nov.
, spire narrowly to broadly acuminate (spire angle 49
-
62°). Apex pointed. Embryonic whorls smoothly granulate. Later whorls with characteristically coarse, few and widely spaced ribs (5
-
10 per mm on penultimate whorl). Sutures deep. Umbilicus closed or nearly so. Peristome incomplete parietally. Outer palatal surface of aperture with a depression corresponding to the palatal tooth. Dentition characteristically simple, 4-fold to 5-fold, consisting of: one lamella-like parietal tooth; one slab-like palatal tooth without parieto-palatal sinus; one basal denticle; and one deep-set columellar baffle, always visible, sometimes with a very slight, shallower columellar tooth. Juvenile shells and anatomy unknown.
Range and habitat
Lowlands of extreme southeastern
Kenya
, including Taru Desert. This subspecies has also been recorded from
Malindi
(
Verdcourt 1962: 17
) and Mrima Hill (
4.48°S
,
39.25°E
) (
Verdcourt 2006
).
Verdcourt (2000)
suggested the habitat was “bushland to forest”, in contrast to “woodland/forest” for
D. r. radius
comb. nov.
Shells of both
D. r. radius
comb. nov.
and
D. r. calva
comb. et stat. nov.
have been found in river debris near
Mombasa
, but may have been washed in from different localities.
Remarks
The
lectotype
and similar material of this subspecies (
Figs 6-8
,
51
) differ from
D. r. radius
comb. nov.
in the more widely spaced ribs, more columnar shape and simpler dentition, although some specimens seem to show intermediate characters. Verdcourt evidently had difficulty separating them. Although
Verdcourt (1962: 17)
suggested
G. calva
was “scarcely more than a variety of
G. radius
”, it keyed out in a separate part of his key, with
radius
appearing in two other places (1962: 13, 22). The second of these (p. 22) was listed as “
Gulella radius
(Preston)
var. (K [
Kenya
], Mrima Hill Forest)”. Verdcourt’s measurements, description, and range of apertural tooth formulas allow attribution of this taxon to
D. r. calva
comb. et stat. nov
.. In his later checklists,
Verdcourt (1983: 234
;
2006: 48-49
) maintained the two as separate species, and gave Mrima Hill as a locality for
calva
but not
radius
. He also kept them apart in his list of coastal molluscs (2000). Thus it appears likely that he later decided that (1962: 22) “
radius
var.” belonged to what we treat as
D. r. calva
comb. et stat. nov.
and not to what we treat as
D. r. radius
comb. nov.
It also appears that he decided not to separate the two taxa. We too found this a difficult decision to take, owing to the morphological, habitat and distributional differences, which may of course be interrelated. To acknowledge this difficulty, and the potential difficulties in assigning future material to either, we rank
calva
as a subspecies of
radius
.