Calantica arcuata Chan & Hayashi, 2012, n. sp.
Creators: name: Chan, Benny K. K.
name: Hayashi, Ryota
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Maxillopoda
Pedunculata
Calanticidae
Calantica
Calantica arcuata

description: Calantica arcuata n. sp.
(Figs. 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 A, 3A) arranged in 2 whorls, with capitular armourment of S-T surrounded by R-RL-L-CL-C-SC (Figs 2 A, 3A). Capitular plates covered by thick, chitinous coating (Figs 2 A, 3A). Carina long, one third of carina extending beyond carinal margin of tergum, umbo apical, apex acute, curving outward (Figs 2 A, 3A). Tergum pentagonal, umbo apical, basal margin shortest. Scutum almost equilateral triangular, umbo apical (Figs 2 A, 3A). Rostrolatus triangularly pyramidal, umbo apical, apex extending outward (laterally) and downward (Figs 2 A, 3A, B). Latus triangularly pyramidal, umbo apical, apex extending outward (laterally) and upwards (Figs 2 A, 3A, B). Carinolatus triangularly pyramidal, umbo apical, apex extending beyond carinal margin (Figs 2 A, 3A). Sub-carina pyramidal, umbo apical, apex extending beyond carinal margin (Fig. 3 A). Rostrum globular, small, located at base of junction between paired scuta (Fig. 3 B).
Peduncle covered by thick cuticle with scattered setae (Figs 2 A, 3A).
Maxilla rectangular, covered with simple setae (Fig. 4 A). Maxillule rectangular, cutting margin without notch, margin convex with 15 simple setae (Fig. 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 D, E). Mandibular palps triangular, with dense serrulate setae distally (Fig. 4 F). Labrum concave, without notch, 6–8 sharp teeth on each side of cutting margin (Fig. 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 C), rami with simple setae. Cirrus II with anterior ramus 8-segmented, posterior ramus 9-segmented (Fig. 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 E), setae simple. Cirrus IV with both anterior and posterior rami 11-segmented (Fig. 3 F), inner margin of basipodite with 2 extended lobes, margin around lobes covered with simple and serrulate setae (Fig. 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 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 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 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 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 A, 16I). The long carina is also present in juvenile specimens (CL 5.1 mm, NMNS-6690-001; Fig.2 A), suggesting this character has been developed at an earlier stage of ontogeny (Fig. 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 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 B, C). Such features have not been reported in other Calantica species.
description: Published as part of Chan, Benny K. K. & Hayashi, Ryota, 2012, Epibiotic barnacles (Crustacea: Cirripedia: Thoracica) collected by the Kumejima 2009 Expedition, with descriptions of two new species *, pp. 21-48 in Zootaxa 3367 on pages 23-24, DOI: 10.5281/zenodo.281652