Panaietis incamerata Stebbing, 1900

Uyeno, Daisuke, 2016, Copepods (Cyclopoida) associated with top shells (Vestigastropoda: Trochoidea: Tegulidae) from coastal waters in southern Japan, with descriptions of three new species, Zootaxa 4200 (1), pp. 109-130 : 110-111

Panaietis incamerata Stebbing, 1900

( Figs 1–3)

Panaietis incamerata Stebbing, 1900: 666 –667, Pl. LXX. Panaietis incamerata: Monod & Dollfus, 1932 , 157, 162. Panaietis incamerata: Monod, 1934 , 213–218.

Panaietis incamerata: Monod & Dollfus, 1934 , 309–315.

Materials examined. 4 adult females and 3 adult males ( NSMT –Cr 24619), ex Tectus niloticus (Linnaeus, 1767) (Vestigastropoda: Trochoidea: Tegulidae ), off Saneku (28°12'N, 129°12'E), Kakeroma-jima Island, Oshima Strait, 29 April, 2015, leg. D. Uyeno, S. Yokoyama ; 2 adult females ( NSMT –Cr 24620), ex T. niloticus , off Osaki (24°25'N, 124° 4'E), Ishigaki-jima Island, East China Sea, 30 May, 2015, leg. D. Uyeno ; 3 adult females and 1 adult male ( NSMT –Cr 24621), ex T. niloticus , off Itchachi (26°20'N, 126°43'E), Kume-jima Island, East China Sea, 3 March, 2012, leg. D. Uyeno, Y. Fujita, T. Naruse ; 2 adult females (RUMF-ZC-04354), ex T. niloticus , off Henokozaki Cape (26°31'N, 128° 4'E), Oura Bay, Okinawa-jima Island, North Pacific Ocean, 12 April, 2012, leg. D. Uyeno, S. Nishihira ; 2 adult females and 1 adult male (KAUM-AT-287), ex T. niloticus , off Manza (26°30'N, 127°50'E), Onna, Okinawa-jima Island, East China Sea, 30 March, 2012, leg. D. Uyeno ; 1 adult female ( NHMUK 1934.4.20.1), off Port Blair , Andaman Islands, India ; 1 adult female (NHMUK 1934.4.20.2); 1 adult female ( NHMUK 1949.11.15.2), Port Blair , Andaman Islands, India.

Description of adult female. Body ( Fig. 1 A) cyclopiform, 5.30–7.63 (6.25 ± 0.70) long (n = 13), depressed dorso-ventrally with greatest width at cephalosome; external segmentation distinct. Cephalosome distinctly articulated from first pedigerous somite, wider than long, 0.87–1.17 (1.04 ± 0.07) × 1.11–1.62 (1.50 ± 0.13). First to fourth pedigerous somites and urosomites free. First pedigerous somite bearing pair of dorsal posterolateral lobes partially overlapping second pedigerous somite. Prosome 1.94–2.52 (2.19 ± 0.19) long. Genital somite bearing pair of posterolateral lobes with bulbous swelling on ventral side ( Fig. 1 A, C), 0.23–0.31 (0.25 ± 0.04) × 0.95–1.20 (1.09 ± 0.07); genital openings situated on ventral side ( Fig. 1 C). Abdomen progressively narrower posteriorly, composed of four free somites, 0.42–0.74 (0.55 ± 0.09) × 0.52–0.71 (0.63 ± 0.05), 0.49–0.80 (0.63 ± 0.11) × 0.52–0.64 (0.59 ± 0.03), 0.42–0.77 (0.57 ± 0.11) × 0.46–0.58 (0.52 ± 0.03), and 0.57–0.95 (0.73 ± 0.11) × 0.38–0.60 (0.48 ± 0.05), respectively. Caudal ramus ( Fig. 1 A, D, E) 5.07–6.56 (5.88 ± 0.48) times longer than wide, 0.88–1.36 (1.18 ± 0.13) × 0.15–0.23 (0.20 ± 0.02), with six setae. Egg sac ( Fig. 1 A) multiseriate, straight, sausage shaped.

Rostrum ( Fig. 1 B) triangular without distinct apex. Antennule ( Fig. 1 F) 7-segmented; armature formula 4, 15, 5, 4, 6 + 1 aesthetasc, 2 + 1 aesthetasc, 7 + 1 aesthetasc; all setae small, naked. Antenna ( Fig. 1 G) 3-segmented, composed of coxobasis and 2-segmented endopod; coxobasis large, bearing simple seta; first endopodal segment bearing seta on inner margin; second endopodal segment bearing four inner setae, inner fused claw, three claws, and two long distal setae. Labrum ( Fig. 1 H) broad, with pair of posterior lobes. Mandible ( Fig. 2 A) with inner lashlike serrated setiform element and apical serrated setiform element with two hyaline outer teeth at base of outer lash. Maxillule ( Fig. 2 B) represented by simple lobe armed with spherical protrusion and four simple elements. Maxilla ( Fig. 2 C) 2-segmented; basal segment unarmed; terminal segment bearing five sharp processes and two setae. Maxilliped ( Fig. 2 D) 2-segmented, composed of unarmed syncoxa and rod-shaped basis bearing single apical blunt element.

Legs 1 to 4 ( Fig. 2 E–H) biramous, bearing 3-segmented rami. Leg armature formula as follows:

Coxa Basis Exopod Endopod

Leg 1 0-0 1-0 I-0; I-0; III, I, 3 0-0; 0-0; II, 1, 2 Leg 2 0-0 1-0 I-0; I-0; III, I, 3 0-0; 0-0; II, I, 2 Leg 3 0-0 1-0 I-0; I-0; III, I, 3 0-0; 0-0; III, I, 2 Leg 4 0-0 1-0 I-0; I-0; III, I, 3 0-0; 0-0; III, I, 1 Intercoxal sclerite ( Fig. 2 E–H) of legs 1 to 4 unornamented. All spines spatulate. Both rami of legs 1 to 4 bearing rows of fine spinules on base of spines. Marginal row of fine spinules present on outer margin of basal endopodal segment of legs 1 and 2 and along middle segment of legs 1 to 3. Leg 5 ( Fig. 2 I) consisting of dorsolateral seta on fifth pedigerous somite and free exopod; exopod elongate, rod-shaped, bearing three blunt spines and simple seta. Leg 6 ( Fig. 1 C) represented by two small elements at genital opening.

Description of adult male. Body ( Fig. 3 A) cyclopiform, 3.58–5.27 (4.60 ± 0.69) long (n = 5), depressed dorso-ventrally with greatest width at cephalosome; external segmentations distinct. Cephalosome distinctly articulated from first pedigerous somite, wider than long, 0.72–0.92 (0.83 ± 0.09) × 0.96–1.35 (1.17 ± 0.16). First to fourth pedigerous somites and urosomites free. Prosome length 1.46–1.74 (1.64 ± 0.12). Genital somite ( Fig. 3 A, B) wider than long, 0.15–0.28 (0.20 ± 0.05) × 0.57–0.87 (0.70 ± 0.12). Abdomen progressively narrowing posteriorly, composed of four free somites, 0.32–0.50 (0.43 ± 0.08) × 0.42–0.61 (0.51 ± 0.08), 0.29–0.59 (0.46 ± 0.12) × 0.39–0.53 (0.46 ± 0.06), 0.33–0.55 (0.45 ± 0.09) × 0.32–0.48 (0.41 ± 0.06), and 0.41–0.67 (0.56 ± 0.11) × 0.32–0.45 (0.37 ± 0.06), respectively. Caudal ramus ( Fig. 3 A) 4.44–6.96 (5.93 ± 1.00) times longer than wide, 0.62–1.07 (0.88 ± 0.22) × 0.11–0.19 (0.15 ± 0.03), with six setae.

Antennule, antenna, mandible, and maxilla as in female. Maxillule ( Fig. 3 D) as in female, except replacement of spherical protrusion by small knob-like protrusion. Maxilliped ( Fig. 3 E, F) 4-segmented; basal segment rod-like bearing patch of small spinules; second segment bearing two setae; third segment small, with two elements; terminal claw curved, bearing element proximally and row of spinules on inner margin. Armature formula of legs 1 to 4 as in female. Legs 1 and 2 bearing endopod with single and two pointed outer processes on middle and terminal segments, respectively. Leg 5 as in female. Leg 6 ( Fig. 3 B, C) represented by two simple setae on genital operculum.

Remarks. Panaietis incamerata was originally described from an unidentified gastropod off Louisiade Archipelago, Papua New Guinea ( Stebbing 1900). Subsequently, the copepod was reported off Port Blair, Andaman Islands (Monod 1934; Monod & Dollfus 1934). Ho (1981) claimed that the leg 5 of the specimen of Andaman Islands is actually longer than that of the original description. However, he did not conclude about the conspecificity of the specimens, once Stebbing (1900) did not detail its description. Currently, three other congeners of Panaietis are known from marine gastropods ( Sars 1918; Yamaguti 1936; Izawa 1976). My examination of P. incamerata based on newly collected specimens in Japanese waters and museum specimens collected from the type locality revealed some characteristics not shared with other congeners. Panaietis incamerata differs from P. haliotis Yamaguti, 1936 and P. malleolata ( Sars, 1918) in having following characters: legs 1 and 2 bearing spatulate spines (vs. sharp spines in the other species); third segment of both rami of legs 1 and 2 bearing three and two setae (vs. four and three setae) (see Sars 1918, pl. CXII; Yamaguti, 1936). Panaietis yamagutii Izawa, 1976 is clearly distinguished from P. incamerata by the following characters: third segment of both rami of legs 1 bearing four setae in female (vs. three setae); genital openings situated on dorsal side in female (vs. ventral position with one small lobe on adjacent surface); free exopod of leg 5 small, situated on posteroventral side of pedigerous somite on both sexes (vs. elongate, situated on lateral side) ( Yamaguti, 1936; Izawa, 1976; present study).

Attachment site. The pharynx and esophagus.

Newly established Japanese name for species. Takasegai-no-haramushi.