Scolecodespugetensis, 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 : 603-605

Scolecodespugetensis sp. nov.

( Figs. 406 , 407 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21436 ) , paratypes (8 intact ♀♀, MNHN-IU-2014- 21437), and dissected paratypes (3 ♀♀, figured) in thin membranous cysts in a solitary ascidian, Pyura sp., Puget Sound, Washington, USA.

Etymology. The name of the new species refers to its type locality.

Descriptionoffemale. Body ( Fig. 406A ) elongate, cylindrical, straight or curved, consisting of prosome and unsegmented free abdomen. Body length variable, 9.25 mmin relatively small, figured specimen; body width 0.93 mm. Prosome unsegmented: cephalosome notarticulated from remaining part of prosome, but discernible by lateral expansions( Fig.406B );antennalandrostralregionnarrow. All legs inserted in pedigerous region confined to anterior part of prosome. Genital openings present in posterior region of prosome. Abdomen ( Fig. 406C ) unsegmented, as long as wide, positioned posteroventrally on prosome. Caudal rami ( Fig. 406D ) 2.6 timeslongerthan wide (140×54 μm), narrowing in middle and ornamented with numerous papillae scattered over surface: armed with 6 setae (2 outer lateral, 2 subdistal, and 2 distal).

Rostrum ( Fig. 406E ) evenly tapering, aslongas wide. Antennule ( Fig. 406F ) unsegmented but clearly divisible into 2 parts; proximal part extremely swollen, globular, armed with 3 small setae distally; distal part narrow, digitiform, armed with 11 setae and 1 aesthetasc. Antenna ( Fig. 406G ) 3-segmented; coxa and basis broad and unarmed; unsegmentedendopod bearing 2 inner and 3 or 4 outer, minute setae, plus straight terminal claw.

Labrum hardly observable. Mouthparts consisting of mandible, maxillule, and maxilla, all represented by unsegmented lobes bearing plumose setae. Mandible ( Fig. 406H ) with 3 long medial and 2 to 4 (3 is common) shorter apical setae. Maxillule ( Fig. 406I ) with 3 long and 3 short setae (2 medial, 3 apical, and 1 outer). Maxilla ( Fig. 406J ) consisting of broader proximal half and narrower distal half (interpretable as 2-segmented condition depending on viewing angle), armed with 1 seta proximally and 3 setaeon apex; ornamented 2 patches of setules and more than 10 papillae. Maxilliped absent.

Legs 1–4 ( Figs. 406K, L , 407A, B ) biramous, each with incompletely 2-segmented protopod, 2-segmented exopod, and unsegmented endopod. Protopods of legs 1– 4 each with outer seta derived from basis; other armature elements absent. All setae on rami short and broad, with nipple-like tip. Number of setae variable between individuals and between left and right legs in single individual. Armature formula for legs 1–4 as follows:

	Protopod	Exopod	Endopod
Leg 1	1-0	1-0; 8 to 9	11 to 14
Leg 2	1-0	1-0; 11 to 17	15 to 21
Leg 3	1-0	1-0; 15 to 16	15 to 19
Leg 4	1-0	1-0; 15 to 17	15 to 19
Leg 5	absent.

Male. Unknown.

Remarks. Scolecodes pugetensis sp. nov. is similar to the type species, S. huntsmani and both species can inhabit solitary ascidians of the same genus ( Pyura ) in the same zoogeographic region. The number of setae on the swimminglegsobservedby Illg (1958, 1970b) fallswithin the range of variability exhibited in our material. The mandible, maxillule, and maxilla of female S. huntsmani illustrated by Dudley (1966) are not significantly different from these limbs in our specimens. Despite these similarities and the variability observed, these two species are not conspecific because the exopods of legs 1–4 are 2-segmented in S. pugetensis sp. nov., but only 1-segmented in adults of S. huntsmani as described by Illg (1958) and illustrated by Illg (1970b). Dudley (1966) also recorded 1-segmented rami inlegs 1–4 of the female copepodid V of S. huntsmani . The segmentation does not appear to exhibit variability and we therefore establish a new species to accommodate the form with 2-segmented exopods in legs 1–4.

Figures

FIGURE 406. Scolecodes pugetensis sp. nov., female. A, habitus, right; B, cephalosome, dorsal; C, posterior end of prosome and urosome, ventral; D, left caudal ramus, ventral; E, rostrum; F, antennule; G, antenna; H, mandible; I, maxillule; J, maxilla; K, leg 1; L, leg 2. Scale bars: A, 1 mm; B, C, 0.1 mm; D, E, K, L, 0.05 mm; F–J, 0.02 mm.

FIGURE 407. Scolecodes pugetensis sp. nov., female. A, leg 3; B, leg 4. Scale bars: 0.05 mm.