Pseudanthessius imo Uyeno, 2016, n. sp.
Creators: name: Uyeno, Daisuke
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Maxillopoda
Poecilostomatoida
Pseudanthessiidae
Pseudanthessius
Pseudanthessius imo

description: Pseudanthessius imo n. sp.
(Figs 10–12)
Type material. Holotype: adult female (NSMT –Cr 24630), ex Tectus niloticus (Linnaeus, 1767) (Vestigastropoda: Trochoidea: Tegulidae), off Saneku (28°12'N, 129°12'E), Kakeroma Island, Oshima Strait, 29 April, 2015, leg. D. Uyeno, S. Yokoyama. Allotype: adult male (NSMT–Cr 24631), collection data same as those of holotype. Paratypes: 2 adult females and 2 adult males (NSMT–Cr 24632), collection data same as those of holotype
Additional material. 1 adult female and 1 adult male (NSMT –Cr 24633), (NSMT –Cr 24633), ex T. niloticus, off Itchachi (26°20'N, 126°43'E), Kume Island, East China Sea, 3 March, 2012, leg. D. Uyeno, Y. Fujita, T. Naruse.
Description of holotype. Adult female. Body (Fig. 10 A) cyclopiform, 2.94 long, depressed dorso-ventrally with greatest width at cephalosome; external segmentation distinct. Cephalosome distinctly articulated from first pedigerous somite, wider than long, 0.63 × 0.93. First to fourth pedigerous somites and urosomites free. Prosome 1.50 long. Genital double somite wider than long (Fig. 10 A), 0.47 × 0.32. Abdomen progressively narrower posteriorly, composed of three free somites, 0.25 × 0.26, 0.18 × 0.21, and 0.19 × 0.20, respectively. Caudal ramus (Fig. 10 A, D) 2.85 times longer than wide, 0.23 × 0.08, with six setae.
Rostrum (Fig. 10 B) triangular, bearing distinct apex with round margin. Post-rostral process situated between bases of antennae (Fig. 10 B). Antennule (Fig. 10 E) 7-segmented; armature formula 4, 14, 6, 3, 4 + 1 aesthetasc, 2 + 1 aesthetasc, 7 + 1 aesthetasc; all setae naked. Antenna (Fig. 10 F) 4-segmented, composed of coxobasis and 3- segmented endopod; coxobasis large, bearing single naked seta; first endopodal segment bearing simple seta on inner margin; second endopodal segment bearing three inner setae; third endopodal segment 1.44 times longer than wide, 61 × 43 µm, bearing four claws, one of them being elongate and three setae on distal part. Labrum (Fig. 10 G) broad, bearing pair of posterior lobes. Mandible (Fig. 10 H) bearing serrated blade with single hyaline tooth at base of convex margin of blade. Maxillule (Fig. 11 A) represented by simple lobe armed with single inner and three distal setae. Maxilla (Fig.11 B) 2-segmented; basal segment unarmed; terminal segment bearing serrated blade and three setae; inner seta large and spinulose. Maxilliped (Fig. 11 C) 3-segmented, composed of unarmed syncoxa, basis bearing two simple setae, and conical endopodal segment with two simple elements.
Legs 1 to 4 (Fig. 11 D–G) biramous, with 3-segmented rami. Leg 4 endopod unsegmented, almost as long as exopod, and with sinuous margins. Leg armature formula as follows:
Coxa Basis Exopod Endopod
Leg 1 0-1 1-0 I-0; I-1; III, I, 4 0-1; 0-1; I, 2, 3 Leg 2 0-1 1-0 I-0; I-1; III, I, 5 0-1; 0-2; II, I, 3 Leg 3 0-1 1-0 I-0; I-1; III, I, 5 0-1; 0-2; II, I, 2 Leg 4 0-1 1-0 I-0; I-1; III, I, 5 II
Intercoxal sclerites (Fig. 11 D–G) of legs 1 to 4 unornamented. Leg 1 bearing basis with row of hair-like setules on inner margin. All spines spatulate with serrated margins and terminal flagellum. Both rami of legs 1 to 4 bearing rows of hair-like setules on outer and inner margins, except inner margin of basal segment of endopods on legs 1 to 3. Basal and middle endopodal segments of legs 1 to 3 each bearing row of fine spinules along distal margin and distal pointed projection on outer margin. Terminal endopodal segments of legs 1 and 2 each bearing single pointed projection on outer margin. Leg 5 (Fig. 11 H) represented by simple spine and two naked setae. Leg 6 (Fig. 10 C) represented by two small elements at genital opening.
Description of allotype. Adult male. Body (Fig. 12 A) cyclopiform, 2.43 long, depressed dorso-ventrally with greatest width at cephalosome; external segmentations distinct. Cephalosome distinctly articulated from first pedigerous somite, wider than long, 0.55 × 0.80. First to fourth pedigerous somite and urosomites free. Prosome 1.14 long. Genital somite (Fig. 12 A, B), 0.23 × 0.35. Abdomen progressively narrower posteriorly, composed of four free somites, 0.23 × 0.28, 0.20 × 0.24, 0.16 × 0.20, and 0.16 × 0.18, respectively. Caudal ramus (Fig. 12 A) 3.77 times longer than wide, 0.22 × 0.06, with six setae.
Antennule, antenna, mandible, maxillule, and maxilla as in female. Antenna bearing third endopodal segment 1.48 times longer than wide, 57 × 38 µm. Maxilliped (Fig. 12 D) 4-segmented; basal segment unarmed; second segment bearing two setae and row of fine spinules; third segment small without armature; terminal claw curved bearing two basal setae. Armature formula of legs 1 to 5 as in female. Leg 6 (Fig. 12 B, C) represented by two simple setae on genital operculum.
Variability. Morphology of paratypes and other female specimens as in holotype. Measurements of the paratypes and other specimens (n = 3) as follows: body length 2.08–2.51 (2.31 ± 0.22); cephalosome length 0.58–0.65 (0.63 ± 0.04); cephalosome width 0.82–0.98 (0.90 ± 0.08); prosome length 1.05–1.33 (1.23 ± 0.15); genital double somite length 0.30–0.36 (0.33 ± 0.03); genital double somite width 0.29–0.37 (0.34 ± 0.04); first urosomite length 0.15–0.21 (0.19 ± 0.04); first urosomite width 0.27–0.30 (0.29 ± 0.02); second urosomite length 0.12–0.17 (0.14 ± 0.03); second urosomite width 0.22–0.28 (0.25 ± 0.03); anal somite length 0.17–0.19 (0.18 ± 0.01); anal somite width 0.20–0.23 (0.22 ± 0.01); caudal ramus length 0.21–0.26 (0.24 ± 0.02); caudal ramus width 0.07; length of third endopodal segment of antenna 57–74 (65 ± 8) µm; width of third endopodal segment of antenna 38–61 (46 ± 13) µm. Caudal ramus 3.00–3.56 (3.35 ± 0.31) times longer than wide. Third endopodal segment of antenna 1.21–1.65 (1.46 ± 0.23) times longer than wide.
Morphology of paratypes and other male specimens as in allotype. Measurements of male paratypes and additional specimens (n = 3) as follows: body length 2.08–2.30 (2.15 ± 0.13); cephalosome length 0.51–0.63 (0.58 ± 0.06); cephalosome width 0.68–0.85 (0.75 ± 0.09); prosome length 0.96–1.14 (1.03 ± 0.10); genital somite length 0.18–0.26 (0.22 ± 0.04); genital somite width 0.31–0.43 (0.37 ± 0.06); first urosomite length 0.17; first urosomite width 0.25–0.31 (0.28 ± 0.03); second urosomite length 0.18–0.20 (0.19 ± 0.01); second urosomite width 0.23–0.28 (0.25 ± 0.02); third urosomite length 0.13–0.16 (0.14 ± 0.02); third urosomite width 0.18–0.23 (0.20 ± 0.03); anal somite length 0.12–0.15 (0.14 ± 0.01); anal somite width 0.17–0.19 (0.18 ± 0.01); caudal ramus length 0.18–0.24 (0.21 ± 0.03); caudal ramus width 0.06–0.07 (0.07 ± 0.00); length of third endopodal segment of antenna 49–71 (61 ± 11) µm; width of third endopodal segment of antenna 36–42 (38 ± 3) µm. Caudal ramus 2.74–3.69 (3.24 ± 0.48) times longer than wide. Third endopodal segment of antenna 1.33–1.73 (1.59 ± 0.22) times longer than wide.
Remarks. Pseudanthessius imo n. sp. has four spines on the third exopodal segment of leg 4, a character shared with P. spinosus Shin & Kim, 2004 (Shin & Kim, 2004). The new species differs from P. spinosus by having the following characters: caudal ramus 2.5 to 4 times longer than wide (vs. less than 2 times); presence of postrostral process between bases of antenna (vs. process absent); third endopodal segment of antenna less than 2 times longer than wide, with four claws and three setae (vs. about 3 times longer than wide, bearing two claws, one clawlike seta, and three setae); bearing mandible with single hyaline tooth on convex margin (vs. with four small spinules); leg 4 bearing unsegmented endopod with sinuous both lateral margins (vs. with straight margins and two conical distal processes) (see Shin & Kim, 2004).
Attachment site. Mantle cavity.
Etymology. The specific name means “sweet potato” in Japanese. It alludes to shape of the irregularly constricted endopod of leg 4. The name is used as a noun in apposition.
Newly established Japanese name for species. Imo-ashi-kenmijinko.
description: Published as part of Uyeno, Daisuke, 2016, Copepods (Cyclopoida) associated with top shells (Vestigastropoda: Trochoidea: Tegulidae) from coastal waters in southern Japan, with descriptions of three new species, pp. 109-130 in Zootaxa 4200 (1) on pages 124-128, DOI: 10.11646/zootaxa.4200.1.4, http://zenodo.org/record/177778