Paramisophria sinjinensis, Lim & Min, 2013

Lim, Byung-Jin & Min, Gi-Sik, 2013, Two new species of hyperbenthic calanoid copepods (Crustacea: Calanoida: Arietellidae) from South Korea, Journal of Natural History (J. Nat. Hist.) 48 (9 - 10), pp. 523-542 : 526-531

Paramisophria sinjinensis sp. nov.

( Figures 2–5 )

Material examined

Holotype. Dissected adult male (NIBRIV0000263336), 1.41 mm, Sinjindo Island (36 ◦ 40 ′ N, 126 ◦ 08 ′ E), Chungcheongnam-do, South Korea, 2 August 2011, coll. B.J. Lim.

Description of male (holotype, NIBRIV0000263336)

Body ( Figure 2A, B ) compact and almost symmetrical. Rostrum ( Figure 2C ) with a pair of filaments on tip. Cephalosome separated from first pedigerous somite; fourth and fifth pedigerous somites fused and having dorsolateral processes. Urosome fivesegmented. Caudal rami symmetrical, with seven setae and lateral setules on outer margin ( Figure 2D ).

Antennules asymmetrical, left antennule longer than right. Right antennule ( Figure 3A ) 21-segmented. Armature pattern of segments as follows: segment 1 (corresponding to ancestral segments I–III), 7 + 3ae; segments 2 to 18 (IV–XX), 2 + ae; segment 19 (XXI), 1 + ae; segment 20 (XXII), 1; segment 21 (XXIII–XXVIII), 12 + 2ae.

Left antennule ( Figure 3B, C ) 18-segmented. Segment 1 (I–IV), 7 + 4ae; segments 2 to 6 (V–IX), 2 + ae; segment 7 (X), spiniform seta, 1 seta + ae; segment 8 (XI), 2 + ae; segments 9 to 11 (XII–XIV), spiniform seta, 1 seta + ae; segments 12 to 15 (XV–XVIII), 2 + ae; segments 16 (XIX) and 17 (XX), one plate-like spiniform process, 1 + ae; segment 18 (XXI–XXVIII), two plate-like spiniform processes, 14 + 2ae.

Antenna ( Figure 4A ) with unarmed coxa. Basis with subterminal seta. Endopod elongated and two-segmented; first segment with subdistal seta and fine spinules on surface; second segment with three medial and six distal setae. Exopod sevensegmented indistinctly; first to third segments unarmed; fourth to sixth segments bearing one, two and one setae, respectively; distal segment with one medial and two terminal setae.

Gnathobase of mandible ( Figure 4B–D ) with two sharp teeth, one bifurcated tooth, and two rows of spinules; small rounded process occurring between bifurcated tooth and next tooth. Basis with five setae along outer margin. Endopod reduced, with two unequal setae. Exopod five-segmented; each segment having one, one, one, one and two setae.

Maxillule ( Figure 4E ) reduced. Praecoxal arthrite with one short and four long spines. Coxal epipodite with row of eight outer setae. Basis without endites and with row of setules. Endopod reduced, with two unequal setae distally. Exopod ovoid, with three distal setae.

Maxilla ( Figure 4F ) stout. Praecoxa and coxa completely separated. First and second endites of praecoxa with one and two setae, respectively. Each coxal endite with two setae. Basis with one stout naked spine on medial margin. Endopod with six stout and two short pectinate setae.

Maxilliped ( Figure 4G ) developed. Praecox and coxa fused to form syncoxa with one medial and two subdistal setae. Basis and first endopod partially fused to form allobasis with two medial and one distal setae, and patch of spinules. Endopod fivesegmented; each segment having four, four, three, three and four setae.

Swimming legs 1 to 4 ( Figure 5A–D ) with three-segmented rami. Spine and seta formula shown in Table 2.

Coxa of leg 1 ( Figure 5A ) with dense patch of setae on outer margin. First endopodal segment with row of setae on outer distal angle; second and third segments with setules on posterior surface. First exopodal segment with an outer spine reaching end of next segment; second exopodal segment with setules distally, and third segment with setules on posterior surface.

Basis of legs 2 to 4 with two processes on inner distal angle; outer corner of second endopodal segment produced into acute process; distal spine of third exopodal segment longer than other exopodal spines.

Leg 5 ( Figure 2E ) asymmetrical. Left leg without endopod; basis bearing one plumose outer seta. Exopod three-segmented; first segment with outer seta; second segment swollen, with one seta on outer margin; third segment with two small and short setae proximally on outer margin, and one long seta. Right leg uniramous, with basis having one simple seta on posterior surface. Exopod three-segmented indistinctly; first segment with one outer seta; second and third segments incompletely fused; second segment hollowed distally, with one outer seta and dense patch of setules on inner margin; third segment with three setae of unequal lengths.

Female: unknown.

Etymology

The specific name ‘sinjinensis’ is derived from the name of the type locality, Sinjindo Island .

Remarks

This species is distinguished from its congeners by the following combination of characteristics: the presence of three teeth on the gnathobase of the mandible; the absence of an endopod on the male’s left leg 5; hollowed inner distal margin of the male’s second exopodal segment of right leg 5; and incomplete fusion of the second and third exopodal segments on male’s right leg 5.

The males of virtually all species of Paramisophria have an endopod on left leg 5, hence, the lack of this character in the new species can easily be used to distinguish it from almost all other species (except for Paramisophria cluthae T. Scott 1897 and Paramisophria ovata Heinrich 1996 ).

Paramisophria sinjinensis differs from P. cluthae in having dense setae on the outer coxal margin of leg 1 (versus unarmed coxa in P. cluthae ); eight (versus seven) outer setae on the coxal epipodite of the maxillule; and an outer seta on the first exopodal segment of right leg 5 (versus absence of seta).

Paramisophria sinjinensis differs from P. ovata in the following characters: the presence of dorsolateral processes on the last pedigerous somite (versus no process in P. ovata ); the presence of a seta on basis of right leg 5 (versus no seta); the presence of one long and two short setae on the third exopodal segment of left leg 5 (versus one spine and one long seta); and the presence of three setae on the third exopodal segment of right leg 5 (versus two long setae).

Table 3 shows a comparison of P. sinjinensis with other species occurring in northeastern Asia. The male P. sinjinensis is similar to P. itoi , but differs in the following characters: 18-segmented (versus 19-segmented) left antennule; two rows of spinules on the gnathobase of the mandible (versus three rows of spinules); the absence of an endopod on left leg 5 (versus a small bulbous rudimentary endopod); and the presence of a hollow (versus swollen) inner distal margin on the second exopodal segment of right leg 5.

Figures

Figure 2. Paramisophria sinjinensis sp. nov., male, holotype: (A) habitus, dorsal view; (B) habitus, lateral view; (C) rostrum, dorsal view; (D) right caudal ramous, lateral view; (E), leg 5, posterior view. Scale bars = 0.2 mm (A–C), 0.05 mm (D), 0.1 mm (E).

Figure 3. Paramisophria sinjinensis sp. nov., male, holotype: (A) right antennule, posterior view; (B) left antennule, posterior view; (C) segment 18 of left antennule (ancestral segments XXI– XXVIII). Scale bars = 0.1 mm (A, B), 0.05 mm (C).

Figure 4. Paramisophria sinjinensis sp. nov., male, holotype: (A) antenna; (B) mandible; (C) mandibular palp; (D) gnathobase of mandible; (E) maxillule; (F) maxilla; (G) maxilliped. Scale bars = 0.1 mm (A–C, E–G), 0.05 mm (D).

Figure 5. Paramisophria sinjinensis sp. nov., male, holotype: (A) left leg 1, anterior view; (B) left leg 2, anterior view; (C) left leg 3, anterior view; (D) left leg 4, anterior view. Scale bar = 0.1 mm (A–D).