Calantica arcuata, Chan, Benny K. K. & Hayashi, Ryota, 2012
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publication ID |
https://doi.org/ 10.5281/zenodo.281652 |
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DOI |
https://doi.org/10.5281/zenodo.6174485 |
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persistent identifier |
https://treatment.plazi.org/id/03FC87D4-FFDD-8A1E-C7D7-2262564EFF26 |
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treatment provided by |
Plazi |
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scientific name |
Calantica arcuata |
| status |
sp. nov. |
Calantica arcuata n. sp.
( Figs. 2 View FIGURE 2 A, 3, 4)
Material examined. Holotype: RUMF-ZC-1554, one specimen (CL 7.9 mm) attached to a gorgonian coral, trawl 45, 26°19.907´N, 126°43.191´E, 16 Nov. 2009, depth 67.5–76.0 m. Paratypes: RUMF-ZC-1555, two specimens (CL 8.2, 7.8 mm), same data as holotype. NMNS-6690-001, four specimens (CL 8.3, 8.5, 7.6, 5.1 mm), same data as holotype.
Diagnosis. Hermaphrodite capitulum with 13 capitular plates arranged in 2 horizontal whorls, with capitular armourment of S-T surrounded by R-RL-L-CL-C-SC. Carina with apex acute, one third of carina extending beyond carinal margin of tergum, curving outward. Mandible with 3 large teeth, cutting margin convex, small pectinations between teeth. Maxillule rectangular, cutting margin convex, without notch, cutting margin with simple setae. Basipodite of cirri IV and V with extension of 2 lobes on inner margin, all lobe margins with simple and serrulate setae.
Description. Hermaphrodite capitulum trapezoid, with 13 plates ( Figs 2 View FIGURE 2 A, 3A) arranged in 2 whorls, with capitular armourment of S-T surrounded by R-RL-L-CL-C-SC ( Figs 2 View FIGURE 2 A, 3A). Capitular plates covered by thick, chitinous coating ( Figs 2 View FIGURE 2 A, 3A). Carina long, one third of carina extending beyond carinal margin of tergum, umbo apical, apex acute, curving outward ( Figs 2 View FIGURE 2 A, 3A). Tergum pentagonal, umbo apical, basal margin shortest. Scutum almost equilateral triangular, umbo apical ( Figs 2 View FIGURE 2 A, 3A). Rostrolatus triangularly pyramidal, umbo apical, apex extending outward (laterally) and downward ( Figs 2 View FIGURE 2 A, 3A, B). Latus triangularly pyramidal, umbo apical, apex extending outward (laterally) and upwards ( Figs 2 View FIGURE 2 A, 3A, B). Carinolatus triangularly pyramidal, umbo apical, apex extending beyond carinal margin ( Figs 2 View FIGURE 2 A, 3A). Sub-carina pyramidal, umbo apical, apex extending beyond carinal margin ( Fig. 3 View FIGURE 3 A). Rostrum globular, small, located at base of junction between paired scuta ( Fig. 3 View FIGURE 3 B).
Peduncle covered by thick cuticle with scattered setae ( Figs 2 View FIGURE 2 A, 3A).
Maxilla rectangular, covered with simple setae ( Fig. 4 View FIGURE 4 A). Maxillule rectangular, cutting margin without notch, margin convex with 15 simple setae ( Fig. 4 View FIGURE 4 B, C). Mandible with 3 large, sharp teeth, cutting margin convex, pectinations between large teeth, lower margin short, straight, with 6 pectinations, inferior angle with 2 sharp pectinations ( Fig. 4 View FIGURE 4 D, E). Mandibular palps triangular, with dense serrulate setae distally ( Fig. 4 View FIGURE 4 F). Labrum concave, without notch, 6–8 sharp teeth on each side of cutting margin ( Fig. 4 View FIGURE 4 G).
Gap between cirri I and II absent. Cirrus I shortest of all cirri, anterior ramus 11–segmented, posterior ramus 14-segmented ( Fig. 3 View FIGURE 3 C), rami with simple setae. Cirrus II with anterior ramus 8-segmented, posterior ramus 9-segmented ( Fig. 3 View FIGURE 3 D), setae of distal portion of rami fine serrulate, those of mid and proximal portions simple. Cirrus III, anterior ramus 9-segmented, posterior ramus 8-segmented ( Fig. 3 View FIGURE 3 E), setae simple. Cirrus IV with both anterior and posterior rami 11-segmented ( Fig. 3 View FIGURE 3 F), inner margin of basipodite with 2 extended lobes, margin around lobes covered with simple and serrulate setae ( Fig. 3 View FIGURE 3 F). Cirrus V with both anterior and posterior rami 11-segmented, inner region of basipodite with 2 extended lobes, margins around lobes covered with simple and serrulate setae ( Fig. 3 View FIGURE 3 G). Cirrus VI with anterior and posterior rami 12-segmented, posterior region of basipodite without lobe. Caudal appendage non-segmented, leaf-shaped; caudal appendage about 1.5 times height of proximal segment of pedicel of cirrus VI ( Fig. 3 View FIGURE 3 H). Penis short, non-segmented, length similar to height of proximal segment of pedicel of cirrus VI. Complemental males found on inner margin of scutum, composed of carina, rostrum and paired scuta and terga ( Fig. 4 View FIGURE 4 H).
Etymology. Derived from the Latin arcuata , indicating the strongly curved carina, which is a diagnostic character of this new species.
Distribution. At present only recorded from Kumejima Island, Ryukyu Islands, Japan.
Remarks. The current species is classified in Calantica as it has 13 capitular plates arranged in two whorls, with the lower whorls not overlapping the upper whorl. Newman & Jones (2011) reviewed the morphological groupings of Calantica and classified the genus into four groups, based on the number of capitular plates. Group I contains nine species with 13 capitular plates. Group II has one species, which sometimes has an extra second carinolatus. Group III contains two species having 14 capitular plates, including a sub-rostrum. Group IV contains three species with 14 capitular plates, including an additional second latus located at the rostral midline of the first latus. In the present study, C. arcuata n. sp. has 13 capitular plates and thus belongs to Group I. At present, Group I contains C. affinis Broch, 1922 , C. eos ( Pilsbry, 1907) , C. darwini Jones & Hosie, 2009 , C. graphica Rosell, 1991 , C. kruegeri Hiro, 1932 , C. pusilla Utinomi, 1970a , C. studeri ( Weltner, 1922) , C. trispinosa ( Hoek, 1883) and C. arcuata n. sp. ( Fig. 16 View FIGURE 16 A–I).
Calantica arcuata n. sp. differs from all members Group I ( Newman & Jones 2011) by having a diagnostic long (one third of carina extending beyond the tergum) and outward curving carina ( Figs 2 View FIGURE 2 A, 16I). The long carina is also present in juvenile specimens (CL 5.1 mm, NMNS-6690-001; Fig.2 View FIGURE 2 A), suggesting this character has been developed at an earlier stage of ontogeny ( Fig. 2 View FIGURE 2 A). Mandibles of both C. arcuata n. sp. and C. graphica are three toothed, but C. arcuata differs from C. graphica in the morphology of the capitulum. Compared to C. arcuata n. sp., the carinal margin of the tergum in C. graphica is slightly convex, whilst the carinal margin of the tergum of C. arcuata n. sp. is bent and forms a distinct obtuse angle ( Fig. 16 View FIGURE 16 C, I). In addition, C. arcuata n. sp. is distinct from the members of Group I by its rectangularly shaped maxillule with a convex cutting margin, and the presence of extended lobes in the basal region of cirri IV and V ( Fig. 4 View FIGURE 4 B, C). Such features have not been reported in other Calantica species.
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