Sarsarietellus suluensis, Ohtsuka & Nishida & Machida, 2005

Ohtsuka, Susumu, Nishida, Shuhei & Machida, Ryuji J., 2005, Systematics and zoogeography of the deep-sea hyperbenthic family Arietellidae (Copepoda: Calanoida) collected from the Sulu Sea, Journal of Natural History 39 (27), pp. 2483-2514 : 2504-2508

Sarsarietellus suluensis n. sp. ( Figures 11–13 ) Material examined

Adult female (holotype), collected from the central Sulu Sea (08 ° 57.319N, 120 ° 11.319E, 09 ° 03.829N, 120 ° 12.359E; wire out 3600 m; depth 0, 1516 m) with IKMT; 6–7 December 2002 ; appendages mounted on glass slides, and body proper in vial; NHM 2005.161 .

Description

Female (holotype). Body ( Figure 11A, B ) 3.08 mm, robust; prosome ca 3.1 times as long as urosome. Cephalosome with round papilla anterolaterally at each side ( Figure 11A, C ); rostrum ( Figure 11D ) possibly with pair of filaments (missing). Prosomal end asymmetrical, with right side more produced outward ( Figure 11B ); dorsolateral and ventrolateral processes acutely pointed; ventrolateral process reaching beyond posterior margin of genital double-somite. Urosome four-segmented; genital double-somite ( Figure 11E–G ) slightly asymmetrical from dorsal view ( Figure 11B ), but highly from ventral view ( Figure 11E ); genital system remarkably asymmetrical, with right gonopore larger and more anteriorly located than left one; copulatory pore opening beneath irregular ventral protrusion on right side; copulatory duct heavily chitinized, Y-shaped; seminal receptacle tubular, terminating at round tip, about half as long as genital double-somite; anal somite short; caudal rami ( Figure 11B ) symmetrical, ornamented with fine setules along inner margin: seta I rudimentary; seta IV thickest (terminal part missing).

Antennules ( Figure 11H, I ) symmetrical, 23-segmented, reaching posterior margin of pediger 3; fusion pattern and armature as follows: I– III 57+2 ae, IV 52, V 52+ae, VI 52+ae, VII52+ae, VIII 52+ae, IX52+ae, X52+ae, XI52+ae, XII52+ae, XIII52+ae, XIV52+ae, XV52+ae, XVI52+ae, XVII52+ae, XVIII52+ae, XIX52+ae, XX52+ae, XXI 5 2+ae, XXII51, XXIII 51, XXIV –XXV52+2+ae ( Figure 11I ), XXVI– XXVIII 58+ae ( Figure 11I ). First (I– III) to eight (X) segments fringed with long setules along posterior margin. Antenna ( Figure 11J ) with unarmed coxa; basis with serrate seta at inner corner; endopod two-segmented, first segment with minute seta distally, second segment with three inner setae of unequal length and one reduced and five ordinary terminal setae; exopod indistinctly eight-segmented, setal formula 0, 1, 1, 1, 1, 1, 0, 3 (one vestigial).

Mandible ( Figures 11K , 12A ) with two mono- and one bicuspid teeth and two patches of setules along cutting edge; patch of long setules present near base of palp (not shown in Figure 11K ); endopod unisegmented, with one well-developed and one rudimentary seta; exopod five-segmented, setal formula 1, 1, 1, 1, 2. Maxillule ( Figure 12C ) with praecoxal arthrite bearing five naked spines, one process and patch of long setules; coxal endite bearing serrate seta; coxal epipodite with eight setae; basis with two rows of long setules and one vestigial seta; endopod one-segmented, bulbous, with two serrate unequal setae terminally; exopod one-segmented, lobate, with three long setae (one missing in Figure 12C ) terminally. Maxilla ( Figure 12D, E ) with first praecoxal endite bearing two setae and one vestigial element; second praecoxal to second coxal endites each with two serrate setae; basis elongated, bearing relatively short spine with two longitudinal rows of fine setules ( Figure 12E ); endopod indistinctly four-segmented, with setal formula 1, 3, 2, 2. Maxilliped ( Figure 12F–H ) with syncoxa bearing one middle and two subterminal serrate setae and subterminal patch of minute spinules; basis protruded midway, with two serrate setae and patch of fine spinules; first endopodal segment nearly incorporated into basis, with serrate seta; second to fifth endopodal segments bearing four, four, three, and three setae, respectively ( Figure 12F–H ); second endopodal segment elongate; terminal endopodal segment with reduced seta a and long seta b.

Segmentation and seta/spine formula of legs 1–4 ( Figure 13A–F ) as in Protoparamisophria biforaminis . Leg 1 ( Figure 13A, B ) with basis bearing anterodistal row of minute spinules near base of endopod; first and third endopodal segments with patch of fine setules on anterior surface; outer spines on second and third exopodal segments well chitinized. Legs 2 ( Figure 13C, D ) and 3 ( Figure 13E ) similar except for acuteness of process at inner distal corner of basis. Leg 4 ( Figure 13F ) with short basal seta on posterior surface; basal process moderately pointed at inner distal corner.

Leg 5 ( Figure 13G ) almost symmetrical, with coxae and intercoxal sclerite completely fused to form common base; basis bearing plumose seta near outer middle margin on posterior surface; endopod represented by process carrying four plumose setae, acutely pointed at tip; exopod unisegmented, with one long, terminal and four short, outer spines; terminal right process of exopod slightly longer than left one.

Remarks

The new species is readily distinguished from the other congeners based on: (1) welldeveloped dorsolateral and ventrolateral processes of pediger 5; (2) remarkably asymmetrical genital system of the genital double-somite; (3) structure of leg 5 (in particular, the non-expression of suture lines on the exopod).

Phoront of possibly apostome ciliates were found also on the mandibular palp ( Figure 12A, B ) of this species as well as in Metacalanalis hakuhoae (see Figure 3A, F, H, K ).

Etymology

The specific name of the new species, suluensis , refers to the type locality, the Sulu Sea.

Figures

Figure 3. Metacalanalis hakuhoae n. gen., n. sp., female (holotype). (A) Leg 1, posterior; (B) third exopodal segment of leg 1, posterior; (C) outer lateral margin of endopod of leg 1, posterior; (D) inner basal seta of left leg 1; (E) inner basal seta of right leg 1; (F) right leg 2, anterior; (G) third exopodal segment of left leg 2; (H) phoront of apostome ciliates (?) on intercoxal sclerite of leg 2; (I) right leg 3, anterior; (J) second and third exopodal segments of left leg 3, anterior; (K) left leg 4, posterior; (L) first exopodal segment of right leg 4, posterior, second and third segments missing; (M) leg 5, posterior. Phoronts of apostome ciliates (?) indicated by arrowheads. Scale bars in mm.

Figure 11. Sarsarietellus suluensis n. sp., male (holotype). (A) Habitus, lateral; (B) habitus, dorsal; (C) anterolateral papilla of cephalosome; (D) rostrum, anterior, filaments missing; (E) genital double-somite, ventral; (F) genital double-somite, right lateral; (G) genital double-somite, left lateral; (H) antennule; (I) terminal segments of antennule; (J) antenna; (K) mandibular cutting edge. Scale bars in mm.

Figure 12. Sarsarietellus suluensis n. sp., male (holotype). (A) Mandibular palp, phoront of apostome ciliate (?) indicated by arrowhead; (B) phoront of apostome ciliate (?) on mandibular palp; (C) maxillule; (D) maxilla; (E) basal spine of maxilla; (F) maxilliped, some setae omitted; (G) fourth endopodal segment of maxilliped, only smallest seta illustrated; (H) fifth endopodal segment of maxilliped, largest seta omitted. Scale bars in mm.

Figure 13. Sarsarietellus suluensis n. sp., male (holotype). (A) Leg 1, anterior; (B) endopod of leg 1, anterior; (C) leg 2, anterior; (D) outer distal corner of second endopodal segment of leg 2; (E) leg 3, anterior; (F) leg 4, posterior; (G) leg 5, posterior. Scale bars in mm.