Haplostoma symbioticum, Kim & Boxshall, 2021

Kim, Il-Hoi & Boxshall, Geoff A., 2021, Copepods (Cyclopoida) associated with ascidian hosts: Ascidicolidae, Buproridae, Botryllophilidae, and Enteropsidae, with descriptions of 84 new species, Zootaxa 1, pp. 1-286 : 162-164

publication ID	https://doi.org/ 10.11646/zootaxa.4978.1.1
publication LSID	lsid:zoobank.org:pub:9C7C1723-73EB-4FBE-A47A-54627DEB8F93
DOI	https://doi.org/10.5281/zenodo.10530927
persistent identifier	https://treatment.plazi.org/id/3729879B-FF44-FF54-FA93-FDEDD54E1B5C
treatment provided by	Plazi
scientific name	Haplostoma symbioticum
status	sp. nov.

Treatment

Haplostoma symbioticum sp. nov.

( Figs. 105 View FIG , 106 View FIG )

Type material. Holotype ♀ (MNHN-IU-2014-21520) and 1 ♀ paratype (MNHN-IU-2014-17387, dissected) from ieptçclẚnẚdes sp. (MNHN-IT-2008-4855 = MNHN A2 View Materials / LEP/108 ); Baluan Is., Papua New Guinea, CRCHO 555 (02°32.27’S, 147°17.97’E), depth 15 m, Colin-CRRF coll., 23 June 2003. GoogleMaps

Etymology. The specific name is derived from the Greek symbẚç (=living together), referring to its co-occurrence together with e. mammẚferum sp. nov. in the same genus of host in the same geographic region.

Description of female. Body ( Fig. 105A, B View FIG ) small, slightly dorsoventrally depressed; consisting of cephalosome, 4-segmented metasome, and small genitoabdomen. Body length 723 μm; maximum width 270 μm (across last metasomite). Cephalosome 125×188 μm, narrower than first metasomite; metasome gradually broadening posteriorly; articulations between metasomites incomplete, but each metasomite distinctly defined by constrictions. Compound last metasomite with broad dorsal protrusion in middle ( Fig. 105B View FIG ). Genitoabdomen ( Fig. 105C View FIG ) 146×136 μm, obscurely defined from metasome, indistinctly 2-segmented ( Fig. 105D View FIG ), with short posterior somite (free abdomen). Caudal ramus ( Fig. 105D View FIG ) about 1.6 times longer than wide (34×21 μm), armed with 2 blunt setae (1 dorsal and 1 distal); distal seta specialized (with expanded proximal and slender distal halves), giving caudal ramus apparent 2-segmented condition.

Rostrum ( Fig. 105E View FIG ) as short, convex protrusion. Antennule ( Fig. 105F View FIG ) small, stout, 43 μm long, incompletely 3-segmented; armed with 1, 3, and 4 small setae on first to third segments, respectively. Antenna ( Fig. 105G View FIG ) 3- segmented including short first segment (coxa); second segment as long as wide, unarmed; third segment twice as long as wide (24×12 μm); armed with 3 spines, 2 larger distal spines each bearing 1-3 spinules subdistally.

Labrum ( Fig. 105H View FIG ) broad, with nearly parallel lateral margins, convex posterior margin with slightly angular apex; narrow sclerotization stripe present along posterolateral borders. Mandible, maxillule, and maxilla absent. Maxilliped ( Fig. 105I View FIG ) robust, 3-segmented; first segment much wider than long, unarmed; second segment (basis) wider than long, unarmed, with 1 spinulose tubercle near mediodistal corner; third segment (endopod) short, unarmed; terminal claw stout, with tooth-like process on inner proximal surface.

Legs 1-4 ( Fig. 106 View FIG A-D) each consisting of protopod, exopod, and semicircular endopod. Exopods armed with 1 seta plus 4 spines in leg 1, 1 seta plus 3 spines in leg 2, and 1 seta plus 2 spines in legs 3 and 4. Spines on exopods with 1 to several spinules subdistally. Two distal spines on exopods fused at base, appearing as single bifurcate spine. Endopods of legs 1-4 distinct.

Leg 5 ( Fig. 106E View FIG ) as small papilla-like lobe tipped with 2 setae. Leg 6 ( Fig. 106F View FIG ) represented by 2 groups (each group enclosed with hyaline material) of 3 dentiform processes; additional 5 smaller dentiform elements present near leg 6.

Male. Unknown.

Remarks. eaplçstçma symbẚçtẚcum sp. nov. may be differentiated from other congeneric species by the characteristic form and armature of its caudal ramus which bears 1 simple dorsal seta and 1 proximally expanded distal seta. The presence of only 3 spines on the antenna is also an unusual feature within eaplçstçma, because only e.

gẚbberum ( Schellenberg, 1922) was recorded as having 3 spines, although the latter species is not similar to the new species in other respects.

In having a proximal seta on the exopods of legs 1-4, e. symbẚçtẚcum sp. nov. belongs to subgroup 1 as defined by Ooishi (2004b). Members of this subgroup generally have simple spines on the exopods of legs 1-4, with the exception of two species, e. mẚnutum and e. setẚferum, described by Ooishi & Illg (1977), both of which have the two terminal spines on the exopods fused at base, thus appearing as one bifurcate spine, as in e. symbẚçtẚcum sp. nov. In e. mẚnutum and e. setẚferum the caudal ramus bears 3 or more armature elements, the antenna bears 4 armature elements, and the protopods of legs 1-4 bears an outer seta. These differences serve to distinguish both of them from the new species.