Copepods (Cyclopoida) associated with ascidian hosts: Ascidicolidae, Buproridae, Botryllophilidae, and Enteropsidae, with descriptions of 84 new species
Author
Kim, Il-Hoi
m@gwnu
Author
Boxshall, Geoff A.
m@gwnu
text
Zootaxa
2021
1
1
286
journal article
10.11646/zootaxa.4978.1.1
1175-5326
4820443
9C7C1723-73EB-4FBE-A47A-54627DEB8F93
Haplostoma rectangulatum
sp. nov.
(
Fig. 91
)
Type material.
Holotype
♀
(MNHN-IU-2009-5230) and
1 ♀
paratype
(dissected, MNHN-IU-2014-17382) from
mçlysyncratçn
sp.; off
Libanona
,
Sud
Madagascar
,
ATIMO VATAE
Expedition,
Stn TR
01 (
25°00.25´S
,
46°59.4´E
), depth
9 m
,
MNHN
coll.,
28 April 2010
.
Additional material.
1 ♀
(MNHN-IU-2009-5232) in
mçlysyncratçn
sp.,
Port Dauphin
,
Madagascar
,
ATIMO VATAE
expedition,
Stn TR
03 (
25°0.08´S
,
47°0.01´E
), depth
21 m
,
29 April 2010
.
Etymology.
The name of the new species refers to its rectangular abdomen.
Description of female.
Body (
Fig. 91A, B
) eruciform, cylindrical, slightly curved dorsally, consisting cephalosome, indistinctly 5-segmented metasome, and small 2-segmented genitoabdomen. Body length 940 μm; maximum width 290 μm across fourth pedigerous somite. Cephalosome 175×210 μm, narrower than first pedigerous somite; second to fourth pedigerous somites nearly equal in width, each wider than first. Fourth and fifth pedigerous somites demarcated from each other by dorsal and ventral constrictions. Genitoabdomen (
Fig. 91C
) small, 105×120 μm, occupying only 11% of body length, consisting of triangular anterior somite bearing genital apertures dorsally, and narrow, rectangular free abdomen (posterior somite); free abdomen clearly defined from anterior somite due to abrupt narrowing, longer than wide (39×27 μm). Caudal rami absent, but 1 caudal seta may be present on postero- lateral corner of free abdomen (
Fig. 91D
).
Rostrum absent. Antennule (
Fig. 91E
) as small, unsegmented lobe, 24×17 μm, bearing patch of small spinules (or setae?) on apex. Antenna (
Fig. 91F
) stout, 3-segmented; first segment broad but very short and unarmed; second segment longest, unarmed; terminal segment slightly longer than wide, armed with 4 bifurcate spines; spines becoming gradually larger from proximal to distal.
Labrum (
Fig. 91G
) simple, unornamented, with broad distal lobe. Mandible (
Fig. 91G
) vestigial, represented by pair of weak unarmed tubercles, located lateral to labrum. Maxillule and maxilla absent. Maxilliped (
Fig. 91H
) stout, very small, 4-segmented; all segments wider than long; proximal 3 segments unarmed; distal segment bearing unequally bifurcate terminal claw.
Legs 1-4 consisting of protopod and exopod; endopod not discernible; exopods armed only with spines (lacking seta), incompletely articulated from protopod. Exopod of leg 1 (
Fig. 91I
) armed with 5 bifurcate spines and ornamented with spinules near base of each spine. Leg 4 (
Fig. 91J
) slightly larger than leg 1, armed with 4 bifurcate spines and ornamented as in leg 1. Legs 2 and 3 same as leg
4 in
shape and armature.
Leg 5 (
Fig. 91K
) as conical fleshy process on fifth pedigerous somite, directed posterodorsally, bearing 2 small setae (1 dorsal and 1 distal). Leg 6 (
Fig. 91L
) represented by 1 small spine and 1 spiniform process on genital operculum. Four dentiform elements present near leg 6.
Male
.
Unknown.
Remarks.
Ooishi (2009b)
recognized seven species of
eaplçstçma
as “subgroup 2”. In one member of this group,
e
.
bẚspẚnçsum
Ooishi, 2009, the exopods of legs 1-4 are armed with 5, 4, 5, and 5 spines (5-4-5-5 pattern), respectively. The other six species of this group all display a 5-4-4-4 pattern for legs 1-4, in common with
e
.
rectangulatum
sp. nov.
However, only one of these six species,
e
.
dudleyae
Ooishi, 1998
, is comparable with the new species in having a single caudal seta and a vestigial mandible lacking any setal elements.
Ooishi (1998)
described
eK dudleyae
on the basis of material from
Florida
,
USA
and it has a leg 5 represented only by a pair of setae. In contrast, leg 5 of
e
.
rectangulatum
sp. nov.
is well-developed, being represented by a distinct fleshy process bearing 2 setae.
eaplçstçma dudleyae
also has caudal rami, although they are small and lobate, while
e
.
rectangulatum
sp. nov.
lacks defined caudal rami. The latter feature of the new species is unique within the genus. Collectively these differences justify the establishment of the new species.