Schizoproctus mollis Kim & Boxshall 2021, sp. nov.
Creators: name: Kim, Il-Hoi
name: Boxshall, Geoff A.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Maxillopoda
Cyclopoida
Ascidicolidae
Schizoproctus
Schizoproctus mollis

description: Schizoproctus mollis sp. nov.   
(Figs. 77, 78)  
 Type material. Holotype ♀ (MNHN-IU-2018-1982, dissected and mounted on a slide) from Cẚçna ẚntestẚnalẚs (Linnaeus, 1767) (MNHN-IT-2008-1886 = MNHN P1 / CIO/24); Locality and date unknown, MNHN-Saint Joseph coll.   
 Etymology. The specific name is from the Latin mçll (=soft), alluding to the weak exoskeleton of the new species.   
 Description of female. Body (Fig. 77A) dorsoventrally depressed, with soft exoskeleton; body length 1.94 mm. Anterior part of body gradually narrowing posteriorly, distinctly 5-segmented; last metasomite consisting of fused fourth and fifth pedigerous somites. Cephalosome 519×778 μm, with broadly rounded anterior margin. Posterior part of body consisting of genital somite and 3-segmented abdomen; genital and first 2 abdominal somites extremely soft, flexible. Genital apertures not seen. Caudal rami divergent; each ramus (Fig. 77B) about 130×72 μm, armed with 4 distal claws and 2 setae; lengths of claws 110, 115, 39, and 74 μm, respectively, from inner to outer.   
Rostrum small, less than half length of first antennular segment, semicircular, slightly longer than wide. Antennule (Fig. 77C) 5-segmented, evenly tapering; articulation between first 2 segments indistinct; armature formula 10, 4, 2, 2, and 8. Antenna (Fig. 77D) consisting of coxa, basis, and 2-segmented endopod; proximal 3 segments unarmed; second endopodal segment about 4 times longer than wide (185×46 μm), as long as basis; armed with 8 spines; longest second outer spine on distal margin 123 μm long, 0.66 times as long as segment.  
Labrum very weak, flexible. Mandible (Fig. 77E) with 3 teeth on coxal gnathobase; palp with 9 setae arranged as 3, 1, 1, 2, and 2. Maxillule (Fig. 77F) with 8 setae (including minute distalmost seta) on precoxal arthrite, 5 setae (2 inner and 3 outer) on basis, and 3 setae on endopod. Maxilla (Fig. 77G) 3-segmented with incomplete articulation between basis and endopod; armed with 2, 2, and 4 setae on proximal to distal segments. Maxilliped (Fig. 77H) 4-segmented; syncoxa unarmed; basis with 2 setae; first endopodal segment unarmed; second endopodal segment with 1 small seta; terminal claw longer than second endopodal segment.  
Legs 1-4 (Fig. 78 A-D) biramous with 1-segmented rami; coxa unarmed; basis with small outer seta. Exopods of legs 1-4 each with 6 slender spines. Seven setae on endopod of leg 1 comprising 1 unilaterally pinnate and 6 pinnate setae. Armature formula for legs 1-4 as follows:  
     Coxa  Basis  Exopod  Endopod      Leg 1  0-0  1-0  VI  7      Leg 2  0-0  1-0  VI  6      Leg 3  0-0  1-0  VI  4      Leg 4  0-0  0-0  VI  3      
Leg 5 (Fig. 78E) large, lamellate, subcircular, wider than long, 463×504 μm, with 1 seta at outer distal corner and 1 minute setal vestige on middle of distal margin. Leg 6 not seen.  
 Male. Unknown.   
 Remarks. The setation of the endopods of legs 2-4 characterizes S. mçllẚs sp. nov. because the pattern of 6, 4, and 3 setae is unique within the genus (Table 3). Schẚzçprçctus mçllẚs sp. nov. can be also distinguished from its congeners by the combination of a 3-segmented abdomen (shared only with S. vestẚtus and S. trẚpartẚtus sp. nov.), the possession of 4 claws and 2 setae on the caudal ramus (compared to 4 claws and 1 seta in S. vestẚtus, and 5 claws and 1 seta in S. trẚpartẚtus sp. nov.), and by having 2 setae on leg 5 (compared to 1 seta in S. vestẚtus and 4 setae in S. trẚpartẚtus sp. nov.).
description: Published as part of Kim, Il-Hoi & Boxshall, Geoff A., 2021, Copepods (Cyclopoida) associated with ascidian hosts: Ascidicolidae, Buproridae, Botryllophilidae, and Enteropsidae, with descriptions of 84 new species, pp. 1-286 in Zootaxa 1 on pages 120-122, DOI: 10.11646/zootaxa.4978.1.1, http://zenodo.org/record/4820443