Campopera magellanica, Kim & Boxshall, 2020

Kim, Il-Hoi & Boxshall, Geoff A., 2020, Untold diversity: the astonishing species richness of the Notodelphyidae (Copepoda: Cyclopoida), a family of symbiotic copepods associated with ascidians (Tunicata), Megataxa 4 (1), pp. 1-6 : 575-577

Campopera magellanica sp. nov.

( Figs. 385 , 386 )

Typematerial. Holotype (copepodid V ♀, MNHN-IU-2014-21421 ) , paratypes (8 intact copepodids, probably stages III and IV ♀♀, MNHN-IU-2014-21422), dissected paratypes (1 ♀ and 1 copepodid V ♀, figured) from Paramolgula gregaria (Lesson, 1830) , Magellan Strait, date unknown.

Etymology. The new species is named after its type locality, the Strait of Magellan.

Descriptionoffemale. Body ( Fig. 385A ) cylindrical, caterpillar-like, slightlycurvedventrally. Bodylength 3.14 mm, with prosome occupying about 70% of body length. Cephalosome well-defined from metasome; dorsal cephalic shield with expanded ventrolateral margins. Metasome about 2.5 times longerthan wide; 4 pedigerous somites defined only by constrictions. Urosome distinctly narrowerthan prosome, 4-segmented, consistingof genital complex incorporating fifth pedigerous somite and 3 free abdominal somites. Genital complex subdivided by lateral constriction; genital apertures not discernible.Articulation between last 2 abdominalsomites indistinct. Anal somite with distinct posteromedian incision and ornamented with fine setules on lateral surfaces. Caudal ramus ( Fig. 385B ) small, conical, incompletely articulated from anal somite, 1.07 times longer than wide (72×67 μm), ornamented with numerous fine setules on all surfaces: armed with 4 small, papilliform setae (outer lateral, outer subdistal, and 2 distal).

Rostrum ( Fig. 385C ) distinct, longerthanwide; lateral margins parallel in proximal half, but abruptly tapering distally towards blunt apex. Antennule ( Fig. 385D ) 2-segmented; consistingof broad, leaf-like proximal segment and small, nipple-shaped distal segment; proximal segment with traces of articulations; both segments bearing minute setae. Antenna ( Fig. 385E ) stout, 4-segmented; coxa, basis, and first endopodal segment unarmed, each wider than long; distal endopodal segment distinctly narrower than proximal segments, slightly longer than wide (53×44 μm); bearing 6 small setae plusterminal claw, slightly longerthan segment.

Labrum ( Fig. 385F ) shortand broad, distally trilobate, ornamented with fine setules on lobes. Mandible ( Fig. 385G ) consisting of coxa and palp: coxa with broad gnathobase bearing 4 large and 4 small teeth on medial margin; distalmost tooth with minute subsidiary tooth on distal margin: palp consistingof basis, exopod and 2-segmented endopod; armedwith 1 setaon basis, 5 setae on exopod, and 1 and 5 setae on first and second endopodal segments, respectively; all setae small and pinnate, except minute, naked outermost seta on second endopodal segment. Maxillule ( Fig. 385H ) with 9 setae on arthrite, 1 on coxal endite, 2 on epipodite, 4 on exopod, and 4 on fused basis and endopod; exopod incompletely articulated at base; setae densely pinnate except 1 small naked setaon arthrite. Maxilla ( Fig. 385I ) 3-segmented; syncoxawith 3, 2 and 3 setae on first to third endites, respectively; basis bearing 2 setae proximally and drawn out into large, robust claw with blunt tip ornamented with 2 rows of thick, stiff setules along distal third of concave margin; endopod small, unsegmented, bearing 4 small, naked setae. Maxilliped ( Fig. 385J ) unsegmented, lobate, armedwith 7 pinnate setae.

Leg 1 ( Fig. 385K ) biramous with 2-segmented protopod; coxa unarmed; basis lacking outer seta but with inner distal spine; both rami setulose; exopod broad, 2-segmented, bearing 5 small, papilliform setae, 1 on outer distal corner of first segment and 4 on outer and distal margins of second segment; endopod short, lobate, incompletely articulated from basis. Legs 2–4 biramous ( Fig. 386A, B ); protopods indistinctly 2-segmented and unarmed. Exopods larger than endopods; both rami tapering, unsegmented, sparsely setulose, withpartialtrace of articulation and small papilliform setae; 9 papilliform setae on exopod and 6 on endopod of legs 2 and 3, 8 on exopod and 5 on endopod of leg 4. Legs 5 and 6 absent.

Description of Copepodid V female. Body hardly distinguishable from that of adult female. Body length 2.11 mm. Body segmentation more distinct than in adult. Caudal ramus armed and ornamented as in adult. Antennule, antenna, mandible, maxilla, and legs 2–4 as in female. Maxillular arthrite bearing 8 setae. Maxilliped with 5 setae. Leg 1 with unsegmented exopod. Leg 5 absent as in adult.

Male. Unknown.

Remarks. Campopera magellanica sp. nov. and the type species C. michaelseni are very alike in the form of the body, antennule and leg 1, but there are significant differences between the two species, as follows: (1) the caudal ramus of C. magellanica sp. nov. is strongly tapering, but is bluntly rounded distally in C. michaelseni , as figured in the original description ( Schellenberg, 1922); (2) the distal half of the rostrum of C. magellanica sp. nov. is tapering, but the lateral margins of the rostrum of C. michaelseni appear to be parallel in the figure of Schellenberg (1922); (3) the mandibular exopod of C. magellanica sp. nov. is armed with 5 setae, compared to 4 subequal setae as described by Schellenberg (1922); (4) the maxilla of C. magellanica sp. nov. bears 3 setae on the first endite of syncoxa and 4 setae on the endopod, in contrast to 2 and 3 setae, respectively, in C. michaelseni ( Schellenberg, 1922) ; (5) the endopod of leg 1 of C. magellanica sp. nov. is unarmed, but several small papilliform spines were illustrated and described in C. michaelseni ; and (6) leg 5 is absent in C. magellanica sp. nov. whereas it is present in C. michaelseni , according to Schellenberg (1922). These differences are sufficient to support the establishment of the new species.

Figures

FIGURE 385. Campopera magellanica sp. nov., female. A, habitus, right; B, caudal rami, dorsal; C, rostrum; D, antennule; E, antenna; F, labrum; G, mandible; H, maxillule; I, maxilla; J, maxilliped; K, leg 1. Scale bars: A, 0.2 mm; B, E, 0.05 mm; C, 0.1 mm; D, F–K, 0.02 mm.

FIGURE 386. Campopera magellanica sp. nov., female. A, leg 2; B, leg 4. Scale bars: 0.05 mm.