New South African Acanthodrilinae earthworm species, with new data for some earlier known members of the genus Parachilota (Oligochaeta: Acanthodrilidae)
Author
Plisko, J. D.
School of Biological & Conservation Sciences, University of KwaZulu-Natal, P. Bag. X 01, Scottsville, 3209 South Africa, and Natal Museum, P. Bag 9070, Pietermaritzburg, 3200 South Africa
dplisko@nmsa.org.za or jdplisko@saol.com
text
African Invertebrates
2008
2008-12-31
49
2
21
21
http://www.bioone.org/doi/abs/10.5733/afin.049.0203
journal article
55055
10.5733/afin.049.0203
8e4c73ca-f583-42b6-8b8f-2a3a710878e0
2305-2562
7661453
Parachilota timothyi
sp. n.
Figs 6–9
Etymology: Named after Mr Timothy Liversage, who assisted with collection of the
type
series.
Diagnosis: Spermathecal pores in intersegmental furrows 7/8 and 8/9.
Clitellum
saddleshaped on 13,14–1/n17,17. Male pores in 18. Prostatic pores not approximate towards the mid-ventral line, in 17 and 19. Gizzard in 5, well developed. Commencement of intestine in 16. Last pair of lateral hearts in 13. Seminal vesicles paired, in 9 and 11. Spermatheca with unilobate diverticulum attached to basal part of spermathecal duct, extending to joint duct/ampulla and invagination of ampulla.
Description:
External features: Body cylindrical, firm.
Colour
: In life dorsally violet, ventrally brownish grey; alcohol-preserved dorsally violet, extending violet colouration laterally to
c
setal lines, with dark tint on preclitellar and few last posterior segments. Colour fading after extended preservation.
Dimensions
:
Holotype
140×
7 mm
; clitellate
paratypes
120–137×
6–7 mm
; juvenile
30–72 mm
.
Segment number
:
Holotype
153; clitellate
paratypes
163–210; juvenile 109–220.
Prostomium
: Tanylobous with obvious sutures.
Setae
: Paired; on postclitellar segments
aa
:
ab
:
bc
:
cd =
3.5:1.8:4:2; distance between
ab
decreasing on 12–17, increasing on 19–27; this characters clearly observed also on juvenile specimens.
Dorsal pores
: Not observed.
Nephridial pores
: Not observed on
holotype
, although on some individuals noted occasionally in postclitellar intersegmental furrows, in
c
setal lines.
Spermathecal pores
: Paired; in 7/8 and 8/9, in front of
b
.
Female pores
: Paired, in 14 between
aa
.
Clitellum
(
Fig. 6
): Saddle-shaped, whitish yellow, on 13,14–1/n17,17; anterior borders obvious, posterior faint, ventrally extending to
b
setal lines.
Prostatic pores
: Paired in 17 and 19, on prominent swellings encircling
b
setae.
Male pores
: Paired, in 18, small vertical openings ventrally to
b
setae.
Seminal grooves
: Straight or slightly curved.
Papillae
: Prominent swellings, oval, single or paired, in
a
setae line, variably on some segments: 8, 10, 16–20, 21, 20–24.
Figs 6–10.
Parachilota
species
with unilobate diverticulum: (6–9)
P. timothyi
sp. n.
, holotype: (6) anterior part of body, ventrally, 40×; (7) spermathecae of segment 8 and 9, 400×: (8) prostates of 17 and 19, 370×; (9) genital setae of 17 (
a
seta, 9A) and 19 (
b
seta, 9B), 500×; (10)
P. wahlbergi
(
Michaelsen, 1899
)
, spermathecae, 500×. Abbreviations: A – ampulla, Cl – clitellum, D – spermathecal duct, Pd – prostatic duct, Pg – prostatic gland, PR – prostatic pores of 17 and 19, Udv – unilobate diverticulum.
Internal characters:
Salivary glands
: Do not extend backwards beyond septum 4/5.
Gizzard
: In 5, well developed, cylindrical, muscular.
Septa
: 5/6 and 6/7 little thickened; 7/8–10/11 increasing in thickness with 10/11 most thickened; 11/12–15/16 decreasing thickness, becoming less muscular, although strong; some variations in thickness intensity observed, but thickening always obvious in 7/8–15/16.
Intestine
: Commences abruptly in 16 or in the middle of 16; oesophageal longitudinal ridged valves in 14–15.
Lateral hearts
: In 9–13, first pair very thin vessel; last pair in 13 much enlarged.
Nephridia
: Holoic
; thin, elongated coiled loops extend vertically, with no terminal vesicles.
Ovaries
: Not observed.
Testes
and
male funnels
: Ventrally in 10; funnels large, free, iridescent.
Vasa deferentia
: Not
observed.
Seminal vesicles
: Paired, in 9 and 11; anterior pair small, commencing at septum 9/10 ventrolaterally, little lobulated; posterior pair commencing dorsolaterally at septum 10/11 large, brownish, much lobulated.
Spermathecae
(
Fig. 7
): Paired; in 8 and 9; ampulla smooth,
2 mm
long and nearly
2 mm
wide, with external indentation at link with spermathecal duct; duct
1 mm
long; unilobate diverticulum commencing at basal part of spermathecal duct, extending to joint duct/ampulla locates its global ental part in ampulla’s external dent. Iridescent sperm was observed in ental part of diverticulum. Ectal parts of spermathecal ducts enter body wall at 7/8 and 8/9.
Prostates
(
Fig. 8
): Paired, in 17 and 19. Prostatic duct commences as thin, soft tube, extending into thicker, muscular, folded, lobulate gland, confined to one segment; prostatic gland sometimes extends backwards, conically pushing septum into space of neighbouring segment. Ectal parts of prostatic ducts enter body wall in 17 and 19.
Penial setae
(
Fig. 9
):
a
and
b
transferred into penial setae;
5–6 mm
long, slender; steam straight, curved at distal end. Variable in shape and size in individuals collected in the same locality.
Penial setal retractor muscles
: Commence intersegmentally in 17/18 and 19/20.
Holotype
:
Mpumalanga
:
NMSA
/Olig.02204,
17 km
N of Volksrust
(
27°22'S
:
29°53'E
), right side at crossroad to
Sandspruit
, recently burnt grass, moist black soil,
ca
25 cm
deep between roots of various plants,
5.xii.1995
,
JDP
&
T
. Liversage.
Paratypes
:
NMSA
/
Olig.
03639, 10 cl, and
NMSA
/
Olig.
03640, 6 semi-mature, collected with holotype.
KwaZulu-Natal
:
NMSA
/
Olig.
02354,
Ncandu Nat. Res.
(
27°53'30"S
:
29°42'30"E
),
ca
1830 m
, grassland plateau along
Ulumbi
R
., riverine bush mixed with exotic and indigenous trees, moist, rich soil, between roots of diverse plants,
31.i.1996
, 2 cl &
20 in
different states of maturity
, JDP [specimens collected in close vicinity of
P. nkandu
sp. n.
].
Other material examined:
Mpumalanga
: NMSA/Olig.01835, 3 juv,
32 km
W of Volksrust, on bank of Skulspruit R., under willow tree (
Salix
sp.
), marshy, wet soil,
3.xii.1992
, JDP & BRS [indigenous microchaetid
Tritogenia palusicola
Plisko, 1997
, exotic lumbricid
Aporrectodea rosea
(Savigny, 1826)
,
Aporrectodea trapezoides
(Dugès, 1828)
, and megascolecid
Amynthas
sp.
collected in the same sample].
KwaZulu-Natal
:
Ncandu Nat. Res.
grassland plateau around Ulumbi R., at
ca
1830 m
: NMSA/Olig.02353, 4 cl & 16 juv, below bank of Ulumbi R., in indigenous riverine bush, moist, rich soil,
30.i.1996
; NMSA/Olig.02341, 14 cl, grassland plateau, on rocks covered by wet moss, under various plant roots,
29.i.1996
; NMSA/Olig.02344, 15 cl & 11 juv, grassland, moist, sandy soil,
30.i.1996
; NMSA/Olig.02346, 4 cl + 2 juv, and NMSA/ Olig.02347, 3 juv, river bank, in wet sandy soil,
30.i.1996
[with exotic lumbricids
Octolasion lacteum
(Örley, 1881)
and
Dendrodrilus rubidus
(Savigny, 1826)
]; NMSA/Olig.02355 & NMSA/Olig.02356, 2 cl, wet sites, grassland near the river,
29.i.1996
[with endemic microchaetid
Proandricus bourquini
Plisko, 1996
]. All material collected by JDP.
Comparative
material of
Parachilota wittebergensis
Pickford, 1937
examined:
Eastern Cape
:
SAMC
A21616
,
Witteberg Mtns
,
Avoca
farm, on bank of stream, damp soil, 1 cl,
3.v.1928
,
E.G. Pickford
.
Distribution: Known from the outskirt of the Drakensberg Escarpment in the northwestern part of KZN, and in
Mpumalanga
.
Biological notes: The species occurs in grassland and forest soil, on river banks, and near roads. Abundant in
Ncandu Nat. Res.
grassland plateau around the Ulumbi R., at
ca
1830 m
in moist soil, and between various plant roots on the river bank, in indigenous riverine bush, and on scattered grassland plateau rocks covered by moist moss watered by flowing water. The new species occurs together with the indigenous acanthodriline
Parachilota ncandu
sp. n.
, the microchaetids
Proandricus bourquini
Plisko, 1996
and
Tritogenia palusicola
Plisko, 1997
, and with the exotic lumbricids
Aporrectodea rosea
(Savigny, 1826)
,
Aporrectodea trapezoides
(Dugès, 1828)
,
Octolasion lacteum
(Örley, 1881)
,
Dendrodrilus rubidus
(Savigny, 1826)
, and megascolecid
Amynthas
sp.
Discussion:
P
.
timothyi
, having the last pair of lateral hearts in 13 and the intestine commencing in 16, may be related to
P
.
wittebergensis
Pickford, 1937
, known from Witteberg Mountains and Mont-aux-Sources, both sites located south of the occurrence of the new species, in the Drakensberg Mountains. The species differ in the shape of the spermathecae, which are bilobate in
witteberngensis
, attached to anterior face of spermathecal duct, while in
timothyi
the unilobate diverticulum is at the base of the duct, extending to the junction with the ampulla.