Paramisophria koreana, 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 : 531-539

Paramisophria koreana sp. nov.

( Figures 6–11 )

Material examined

Holotype. Dissected adult male (NIBRIV0000263337), 1.47 mm. Geojedo Island (34 ◦ 43 ′ N, 128 ◦ 37 ′ E), Gyeongsangnam-do, South Korea, 21 May 2011, coll. B.J. Lim and Y.A. Noh.

Paratypes. Leg 5 dissected on adult male (NIBRIV0000263340), 1.45 mm, same locality data; dissected adult female (NIBRIV0000263338), 1.64 mm, and dissected male leg 5 (NIBRIV0000263339), 1.49 mm, Geomundo Island (34 ◦ 02 ′ N, 127 ◦ 17 ′ E), Jeollanam-do, South Korea, 16 April 2009, coll. S.S. Hong ; dissected female (NIBRIV0000263342), 1.63 mm and male (NIBRIV0000263341), not measured, Cheongsando Island (34 ◦ 11 ′ N, 126 ◦ 54 ′ E), Jeollanam-do, South Korea, 1 August 2010, coll. M.H. Park.

Description of male (holotype, NIBRIV0000263337)

Body shape ( Figure 6A, B ) similar to P. sinjinensis . Rostrum with a pair of filaments. Cephalosome separated from first pedigerous somite; fourth and fifth pedigerous somites fused and bearing dorsolateral processes. Urosome five-segmented. Caudal rami symmetrical, with seven setae and setules on outer margin.

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

Left antennule ( Figure 7B ) 18-segmented. Segment 1 (I–IV), 7 + 4ae; segments 2 to 6 (V–VII), 2 + ae; segment 7 (VIII–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), 1 plate-like spiniform process, 1 + ae; segment 18 (XXI– XXVIII), 2 plate-like spiniform processes, 14 + 2ae.

Antenna ( Figure 8A, B ) with unarmed coxa. Basis with a seta. Endopod elongated and two-segmented; first segment with subdistal seta and fine spinules distally on the 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 seta, respectively; distal segment with one medial and two terminal setae.

Mandible ( Figure 8C ) with four teeth plus rounded process between second and third teeth, and two rows of spinules on gnathobase. Basis with short setae along outer margin. Endopod reduced, with two unequal setae. Exopod five-segmented; each segment having one, one, one, one and two setae.

Praecoxal arthrite of maxillule ( Figure 8D ) with one short and four long spines. Coxal epipodite with row of eight outer setae. Basis without endites and with setae along outer margin. Endopod with two unequal setae distally. Exopod ovoid, with three distal setae.

Maxilla ( Figure 8E ) 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 four stout and four short pectinate setae.

Maxilliped ( Figure 8F ) developed. Praecoxa 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 on medial margin. Endopod five-segmented; each segment having four, four, three, three and four setae.

Swimming legs 1 to 4 ( Figure 9A–D ) with three-segmented rami. Armature formula of legs 1–4 as in preceding P. sinjinensis .

Leg 5 ( Figure 10A ) 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, and with second and third segments incompletely fused; first segment with one outer seta; second segment swollen, with one seta on outer margin, dense patch of setules covering one small bulge, and soft pointed process subdistally on inner margin; third segment with three setae of unequal lengths.

Description of female (paratype, NIBRIV0000263338)

Body shape ( Figure 11A, B ) similar to male except for four-segmented urosome. Rostrum with a pair of filaments. Caudal rami symmetrical, with seven setae and setules on outer margin. Genital double somite ( Figure 11D ) with a pair of ventrolateral gonopores; single copulatory pore ventrolaterally on right side of genital double somite.

Right antennule ( Figure 11C ) 21-segmented. Armature pattern of segments as follows: segment 1 (corresponding to ancestral segments I–III), 7 + 2ae; segment 2 (IV), 2; segments 3 to 19 (V–XXI), 2 + ae; segment 20 (XXII), 1; segment 21 (XXIII–XXVIII), 12 + 2ae.

Leg 5 ( Figure 11E ) symmetrical. Basis and endopod completely fused with one seta posterolaterally; endopod produced into acute process, with one plumose seta and rounded process. Exopod one-segmented with three short spines along outer margin, one distal spine, and one short subdistal spine; length of distal spine about 2.5 times as long as that of subdistal spine. Exopodal segment produced into acute process distally, positioned between distal spine and subdistal spine.

Etymology

The specific name ‘koreana’ is derived from the name of the type nationality, Korea.

Remarks

The third exopodal segment of left leg 4 ( Figure 9D ) has three outer spines and three inner setae, but right leg 4 ( Figure 9E ) has four outer spines and five inner setae. This seems to be a deformed or regenerative stage. All paratypes have the same armature formula as right leg 4 of the holotype.

Paramisophria koreana resembles P. cluthae in the absence of an endopod on the male’s left leg 5, and the presence of five spines and one seta on the exopod and endopod of the female’s leg 5, respectively. This new species differs from P. cluthae by the presence of eight (versus seven) outer setae on the coxal epipodite of the maxillule, the presence of an outer seta on the first exopodal segment on the male’s right leg 5 (versus no seta), the presence of three unequal (versus subequal) setae on the third exopodal segment on the male’s right leg 5, and the presence of one short and four long spines on the praecoxal arthrite of the maxillule (versus one short and five long spines).

The new species is distinguished from P. sinjinensis by the presence of four teeth on the gnathobase of the mandible (versus three teeth) and a swollen (versus hollow) inner distal margin on the second exopodal segment of right leg 5.

Variation

The second exopodal segment in right leg 5 of male is variable in shape ( Figure 10B–D ). The soft pointed process of second exopodal segment is present or absent on the inner margin. In some cases, second exopodal segment has a soft round process ( Figure 10D ).

Morphological phylogeny of Paramisophria

The results of morphological phylogenetic analysis for 15 species of Paramisophria resulted in 36 equally parsimonious trees with a tree length of 64, consistency index of 0.391, and homoplasy index of 0.609. We selected four most parsimonious trees, which equally showed the lowest f -value. These four trees can be grouped into two pairs, according to the in-group topologies ( Figure 12A, B ).

Paramisophria species fall broadly into four groups, which are essentially similar to the grouping proposed by Jaume et al. (2000) (cf. fig. 24 in Jaume et al. 2000). The first group contains P. giselae , which differs from other species by the presence of a distal seta on the first praecoxal endite of the maxilla (character 9). The second group contains P. japonica , which differs from the other congeners by having basal seta on the maxillulae (character 7) and an inner subapical seta on the endopod of female leg 5 (character 20). The third group includes P. fosshageni , P. itoi , P. galapagensis , P. intermedia , P. platysoma and P. bathyalis , and is united by characters 8, 14 and 22. The two new species ( P. sinjinensis and P. koreana ) clustered with P. ammophila , P. cluthae , P. variabilis , P. reducta and P. mediterranea in the fourth group. They are united by five characters (11, 12, 15, 16 and 19).

The topology of two most parsimonious trees differed only in the positions of P. ammophila and P. cluthae relative to two new species. Paramisophria ammophila clustered with two new species as a sister group ( Figure 12A ), by the absence of a seta on maxillulary coxal endite (character 8) and the presence of a single copulatory pore ventrolaterally on the right side of the genital double somite (character 22). This node is tentative, because there is no information on female P. sinjinensis . However, the two new species also showed a sister-group relationship with P. cluthae ( Figure 12B ), by the absence of a left endopod on male leg 5 (character 23). The two new species appear to be relatively recent offshoots, because the male appendages exhibit a more apomorphic state ( Table 4).

Figures

Figure 6. Paramisophria koreana sp. nov., male, holotype: (A) habitus, dorsal view; (B) habitus, lateral view. Scale bar = 0.25 mm (A, B).

Figure 7. Paramisophria koreana sp. nov., male, holotype: (A) right antennule, posterior view; (B) left antennule, posterior view. Scale bar = 0.1 mm (A, B).

Figure 8. Paramisophria koreana sp. nov., male, holotype: (A) antenna; (B) endopod of antenna; (C) mandible; (D) maxillule; (E) maxilla; (F) maxilliped. Scale bars = 0.1 mm (A, C–F), 0.05 mm (B).

Figure 9. Paramisophria koreana sp. nov., male, holotype: (A) left leg 1, posterior view; (B) left leg 2, posterior view; (C) left leg 3, posterior view; (D) left leg 4, posterior view; (E) third segment of right leg 4, posterior view. Scale bar = 0.1 mm (A–E).

Figure 10. Paramisophria koreana sp. nov., male: (A) leg 5 (holotype), posterior view; (B) second and third segments of right leg 5 (paratype), NIBRIV0000263341; (C) second and third segments of right leg 5 (paratype), NIBRIV0000263339; (D) second and third segments of right leg 5 (paratype), NIBRIV0000263340. Scale bar = 0.1 mm (A–D).

Figure 11. Paramisophria koreana n. sp. nov., female, paratype: (A) habitus, dorsal view; (B) habitus, lateral view; (C) right antennules, posterior view; (D) genital and first abdominal somites, ventral view (arrow indicate copulatory pore); (E) left leg 5. Scale bars = 0.25 mm (A, B), 0.1 mm (C–E).

Figure 12. Two most parsimonius cladograms produced by the cladistic analysis of Paramisophria species.