A revision of Acrenhydrosoma (Copepoda, Harpacticoida) with the establishment of Dyacrenhydrosoma gen. nov. and Paracrenhydrosoma gen. nov. and descriptions of two new species
- Keywords:
-
cletodidae;
acrenhydrosoma;
dyacrenhydrosoma gen. nov.;
paracrenhydrosoma gen. nov.;
man-;
harpacticoida
- Abstract:
- Acrenhydrosoma perplexa is redescribed from cotype and other material. It possesses only two setae on the
antennal exopod, a mandibular palp with three setae, and a maxillulary coxal endite partially fused to a basis which bears
only three setae. The P1 endopod-2 has two armature elements and the P5 baseoendopod, in both sexes, has an outer seta
borne on a submarginal peduncle. The male P5 exopod bears only two setae. The posterior margin of the preanal somite has
a dorsal, dentate, pseudoperculum overlaying the operculum which is situated near the anterior margin of the anal somite.
A new species, with a urosome structure similar to Acrenhydrosoma is described from mangrove forests in S.E. Asia and
is placed in Dyacrenhydrosoma gen. nov. as D. breviseta sp. nov.. It can be distinguished from Acrenhydrosoma by the
absence of a seta on the abexopodal margin of the antennal allobasis, a maxillulary coxal endite (represented by 1 seta)
completely fused to the basis which bears only two setae, reduced armature of the maxilla, short terminal setae without
penicillate tips on P1 exopod-3, only two setae on P2-P4 endopod-2, a female P5 baseoendopod with only one inner spine
and an exopod with only 2 setae.
Material from northern Norway, attributed to Acrenhydrosoma perplexa by T. Scott (1903) is described and placed in
Paracrenhydrosoma gen. nov. as P. normani sp. nov. It is very similar to Acrenhydrosoma maccalli but can be distinguished
from it by features on the P5. A. maccalli and A. karlingi are moved to Paracrenhydrosoma which can be distinguished from
Acrenhydrosoma by the absence of a pseudoperculum on the preanal somite, and also by an operculum situated in the
posterior half of the anal somite, a broader, emarginate rostrum, a mandibular palp with four setae, a maxillulary coxal endite
(bearing two setae) completely separate from a basis bearing six setae, a P1 endopod-2 with three setae and a female P5
exopod with two setae.
- Résumé :
- Révision de Acrenhydrosoma (Copepoda, Harpacticoida) avec établissement de Dyacrenhydrosoma gen. nov. et
Paracrenhydrosoma gen. nov. et description de deux nouvelles espèces.
Acrenhydrosoma perplexa est redécrite à partir d'un cotype et d'autres spécimens. L'espèce possède seulement deux soies
sur l'exopodite antennaire, un palpe mandibulaire avec trois soies, et un endite coxal maxillulaire partiellement fusionné au
basis, qui porte seulement trois soies. L'armature de l'endopodite-2 des P1 est constituée de deux éléments, et le baséoen-
dopodite de P5 présente, chez les deux sexes, une soie externe insérée sur un pédoncule. L'exopodite P5 mâle porte seule-
ment deux soies. Le bord postérieur du somite préanal présente un pseudopercule dorsal dentelé au-dessus de l'opercule qui
est situé près du bord antérieur du somite anal.
Introduction
The genus Acrenhydrosoma Lang, was established by Lang
(1944) to accommodate Cletodes perplexa T. Scott, 1899.
Lang (1936) had previously transferred this species from
Cletodes to Enhydrosoma Boeck, as E. perplexum (T.
Scott), on the basis of the structure of the antennal exopod,
the size of the maxilla and maxilliped, the setation of the P3
and P4 exp-3 and the form of the setae on the P5
baseoendopod. Lang (1944) removed the species from
Enhydrosoma to a new genus primarily because of the
peculiar structure of the P5 in both sexes and the presence
of three setae on the antennal exopod reported by both Scott
(1899) and Sars (1920). However, close inspection of the
descriptions by these latter two authors reveals that there are
sufficient discrepancies between them, and possible errors
in both, to cast doubt on the exact characteristics of this
species and the generic diagnosis of Lang (1944). Since
then, two further species from the west coast of America
have been added to the genus by Lang (1965) and Schizas
& Shirley (1994), as A. karlingi Lang, 1965 and A. maccalli
Schizas & Shirley, 1994.
During a recent study of the diversity of benthic
copep
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