Taxonomy of Stilbonematinae (Nematoda: Desmodoridae): description of two new and three known species and phylogenetic relationships within the family
Author
Armenteros, Maickel
Author
Ruiz-Abierno, Alexei
Author
Decraemer, Wilfrida
text
Zoological Journal of the Linnean Society
2014
Zool. J. Linn. Soc.
2014-04-25
171
1
1
21
http://dx.doi.org/10.1111/zoj.12126
journal article
10.1111/zoj.12126
0024-4082
4890548
AD7CEB9C-3B04-4A87-95BD-A52BA38B1350
STILBONEMA BREVICOLLE
COBB, 1920
Measurements:
Table 1
;
Figures 9
,
10
.
Material examined:
One
♂
,
two ♀
, two J.
Description:
Body habitus slender. Cuticle coarsely striated (annuli 1.4–2.0 μm width). A coat of rodshaped bacteria covering the cuticle; the axis of bacteria cells perpendicular to the cuticle. Head profile anteriorly flattered (but may look globular in some specimens), head capsule well developed, surface with slight depressions. Inner labial sensilla papilliform, outer labial sensilla setiform (∼6 μm long).
14 M.
ARMENTEROS
ET
AL
.
Figure 7.
Robbea porosum
. Specimen 1♂. A, habitus, B, neck region, C, testis and epidermal glands connected to somatic setae, D, tail region.
Four cephalic sensilla setiform (10–15 μm long), two circles of eight subcephalic setae (10–12 μm long), first one anteriorly on the head, second one close to the border of the cephalic capsule; one or two pairs of additional subcephalic setae can occur between both circles. Somatic setae short (5–6 μm long) probably arranged in eight longitudinal rows but few are visible because of the bacterial coat or broken off; somatic setae connected to epidermal glands but not always clear. Amphidial fovea pore-like with corpus gelatum protruding, located subterminally on the head. Pharynx muscular, corpus largely cylindrical but slightly wider near head region, posteriorly widened to a small pyriform bulb; cardia triangular/ elongated and conspicuous. Tail conical, tip smooth and spinneret present.
Male
monorchic, anterior testis to the left of intestine; spicules curved and paired. Six to eight conspicuous cup-like precloacal supplements present at level of pharynx.
Female didelphic, vulva not conspicuous, ovaries antidromously reflexed, both genital branches to the left of intestine.
Remarks:
There are four species of
Stilbonema
formally described:
Stilbonema annulatum
Gerlach, 1963
;
S. brevicolle
Cobb, 1920
;
Stilbonema majum
(
Cobb, 1920
)
, and
Stilbonema smurovi
Tchesunov, 2013
. The descriptions of the first three species are rather poor in morphological details and with only a single male specimen per species. The name
S. majum
appeared in
Urbancik
et al
. (1996a)
but without comments on the transfer of
Laxonema majum
Cobb, 1920
, to
Stilbonema majum
.
Tchesunov (2013)
formally transferred
L. majum
to the genus
Stilbonema
but without explanation. We agree with this classification because
L. majum
in
Cobb (1920)
resembles some features characteristic of the genus
Stilbonema
such as cephalic capsule clearly set-off and coarse annulation. Additionally, specimens identified as
S. majum
in
Urbancik
et al
. (1996a)
were
8.5 mm
in average length, which agrees roughly with the single specimen described as
L. majum
by Cobb (
10 mm
). Our specimens fit well with the original description by
Cobb (1920)
based on specimens from the Caribbean Basin (
Kingston
Harbor,
Jamaica
). The male specimen of
S. annulatum
described by
Gerlach (1963)
is larger than our male specimen (5977 vs. 1870 μm) and was collected far away (i.e. Indian Ocean).