The first proandric species of Tritogenia Kinberg, 1867 from Botswana, Tritogenia talana sp. n. (Clitellata, Crassiclitellata, Tritogeniidae)
Author
Nxele, Thembeka Clara
Author
Plisko, Jadwiga Danuta
Author
Ramongalo, Boipelo K.
text
Zootaxa
2018
2018-10-05
4496
1
214
217
journal article
29267
10.11646/zootaxa.4496.1.17
a161220f-7db6-4ccc-bfaa-de528dab984c
1175-5326
1446761
68B7C32E-BDEB-4C7C-A4F8-BC242DE24351
Tritogenia talana
sp.n.
(
Figure 1
)
Locality
and material.
Botswana
,
Tuli Block region
,
Talana Farms
,
Limpopo
River edge,
22°14'13.7''S
;
29°00'43.8''E
,
359 m
asl
,
05.ii.2016
, T.
Nxele
, B.
Ramongalo
&
N. Serameng
leg.
Holotype
.
Clitellate,
NMSA
/
OLIG
.06946.
Paratypes
.
1 clitellate,
NMSA
/
OLIG
.06726a; 1 clitellate,
NMSA
/
OLIG
.06943a.
Additional material
. 1 juvenile, NMSA/OLIG.06726b, 1 juvenile, NMSA/OLIG.06943b.
Description. External.
Holotype
:
body length
52 mm
, width
4 mm
at tubercula pubertatis; segment number 102.
Paratypes
:
50–60 mm
in length, width
3–4 mm
, segment number 107–110. Colour whitish grey. Prostomium prolobous. Preclitellar segments with secondary annulations: segment 1–3 simple, 1–2 with small horizontal grooves, segment 4–8 with two ringlets of similar size, 9–10 with second ringlet smaller, from 11 and in postclitellar segments simple and randomly annulated. Setae
aa
>
ab
=
cd
<
bc
, all minute, clearly visible on segments near tubercula pubertatis, difficult to locate on preclitella segments. Male pores not observed. Female pores minute on anterior part of segment 14. Spermathecal pore not observed. Clitellum saddle-shaped on 12,13–24,25. Tubercula pubertatis on 18,19–20,21 (figure 1). Genital papillae absent.
Internal
. Septa 4/5 slightly thickened; 5/6–8/9 strongly thickened; other septa thin. Gizzard well developed in 6–7 with septum 6/7 attached. Calciferous glands in 9, large, fused dorsally. Intestinal origin in 12. Typhlosole begins in 20, V-shaped which enlarges into U-shaped. Dorsal blood vessel double in the anterior segments; hearts in 9 and 10; simple in the posterior segments. Nephridia meroic, single duct with coiled loops at the end, two pairs per segment. Proandric. Seminal vesicles lacking. Spermathecae not observed, possibly embedded deep in muscular tissue.
Etymology
. Named after Talana Farms, the
type
locality. Noun in apposition.
Remarks
. This species is most similar to
T. debbieae
Plisko,
2003
in body length (
50–60 mm
), typhlosole (starting as V-shaped) and calciferous glands (not separated dorsally). The new species differs in the extension of the clitellum (12,13–24,25 vs. 13–23) and in thicker septa (4/5–8/9 thickened vs. 4/5–7/8 and all other septa in preclitellar segments thin).
Tritogenia talana
sp. n.
is clearly different from all other
Tritogenia
species by its lack of seminal vesicles.
The earthworm fauna of
Botswana
is currently unknown. Our recent collection resulted in the discovery of an indigenous
Tritogenia
species new to science. This species was collected in the south-eastern part, the Tuli Block. The northern region was also investigated but no
Tritogenia
species were found. The collection of
T. talana
sp. nov.
provides new knowledge on the distribution of
Tritogenia
as it was assumed that possibly the northern boundary for
South
African species is the
Limpopo
River (
Plisko 2012
). There is a possibility that some species may occur in
Mozambique
and
Zimbabwe
along the
Limpopo
River.
The reproductive organs of
T. talana
sp. n.
show some level of degeneration. Most conspicuous is the lack of seminal vesicles, unusual in this genus: all other known species of
Tritogenia
have variably sized seminal vesicles in two segments. Other afrotropical earthworm species that lack seminal vesicles are found in
Madagascar
and belong to the family
Kynotidae
(
Razafindrakoto
et al.
2011
;
Csuzdi
et al.
2012
). Furthermore, spermathecae were not observed in
holotype
and
paratypes
and may be absent as well, or they were deeply embedded in muscle tissue. As noted by
Nxele (2014)
, spermathecae are difficult to observe in
Tritogenia
, especially when embedded in tissue and without sperm, so the possibility remains that they have been overlooked. Finally, this is the first proandric species in this genus, the pair of funnels is small. The reduction in reproductive organs suggests parthenogenesis although more data is needed to validate this. Hermaphrodite species may reproduce parthenogenetically. For example,
Amynthas catenus
Tsai
et al.
, 2001
was found to reproduce parthenogenetically (
Shen
et al.
2011
), based on the study of reproductive organs and DNA ploidy levels. More qualitative collection campaigns in the country may reveal new earthworm species and confirm these suppositions.