Euscalpellum
Creators: name: Chan, Benny K. K.
name: Hayashi, Ryota
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Maxillopoda
Pedunculata
Calanticidae
Euscalpellum

description: Euscalpellum c.f. squamosum Hiro, 1937
(Figs. 2 B, 5, 6)
Euscalpellum squamosum Hiro, 1937b: 391. — Zevina 1981: 89, fig 59.
Euscalpellum stratum. — Hiro 1933: 18, text figs 2, 3, pl. 1, fig. 4, 4a [non E. stratum (Aurivillius, 1894)].
Material examined. RUMF-ZC-1556, one specimen (CL 3.4 mm) on antipatharians, trawl 24, 26°16.322´N, 126°51.631´E, 12 Nov. 2009, depth 150.0–168.0 m. ASIZCR-000225, one specimen (CL 3.8 mm) on antipatharians; trawl 24, 26°16.322´N, 126°51.631´E, 12 Nov. 2009, depth 150.0–168.0 m.
Diagnosis. Capitulum with 15 white, smooth capitular plates. Tergum quadrangular, umbo apical, inframedian latus rhombic, umbo apical. Rostrolatus and carinolatus triangular, umbos apical.
Description. Hermaphrodite capitulum white, elongated, 15 smooth capitular plates, including carina, subcarina, rostrum, paired tergum, scutum, upper latus, inframedian latus, rostrolatus and carinolatus (Fig. 2 B). Tergum quadrangular, umbo apical, occludent margin straight. Scutum quadrangular, umbo at middle of occludent margin. Upper latus almost square to parallelogram. Inframedian latus quadrangular, longitudinal diameter longer than lateral. Carinolatus and rostrolatus triangular, margins straight. Rostrum rhomboid, large, incurved, apex reaching half scutal occludent margin (Fig. 2 B).
Maxilla bi-lobed, distally setose on each lobe (Fig. 5 A). Maxillule slightly notched, region below notch slightly protuberant, 2 large setae above notch, 7 setae below, cutting margin short (Fig. 5 B). Mandible with 4 large teeth excluding inferior angle, 1 small seta present between third and fourth large teeth, lower margin very short, inferior angle ending in sharp seta (Fig. 5 C, D)
Cirrus I with anterior and posterior rami subequal, both rami 12-segmented (Fig. 6 A), setae simple (Fig. 6 B) and serrulate with very fine setules (Fig. 6 C). Cirri II–VI ctenopod, all with simple setae in medial and proximal regions (Fig. 6 D, E), serrulate setae distally (Fig. 6 F). Cirrus II with anterior and posterior rami 9- and 10-segmented, respectively. Cirrus III with anterior and posterior rami 13-segmented. Cirri IV and V with anterior and posterior rami 12- and 13-segmented, respectively. Cirrus VI with anterior and posterior rami 13- and 12-segmented, respectively; intermediate segment of posterior ramus of cirrus VI with 3 pairs of long simple setae and 1 pair of short simple setae. Caudal appendage short, about half height of proximal segment of pedicel of cirrus VI (Fig. 5 E), inner and outer margins with small pectinations, bundle of setae distally (Fig. 5 E). Penis short, half length of cirrus VI (Fig. 5 F).
Complemental males absent in present specimens.
Distribution. Japanese waters, including the Kii Channel, Wakayama Prefecture and Kumejima Island, Ryukyu Islands.
Remarks. The capitular morphology of the current species fits the description of Euscalpellum squamosum by Hiro (1933; 1937b). The mandible described by Hiro (1933) had four teeth, with a small setae between the third and fourth teeth, which is similar to the mandible morphology of the present specimen. The descriptions of Hiro (1933; 1937b) were based on the same, single specimen and recorded no penis. However, we found our specimen has a short penis (Fig. 4 F). The reasons for the absences of a penis in E. squamosum in Hiro (1933; 1937b) is uncertain and could be due to the preservation status of the samples, and Hiro (1937b: 391) claimed “A further investigation on more materials may settle the question whether the present specimen is a pure female or not”. In Zevina‘s (1981) revision of the scalpellid barnacles, the description of E. squamosum was based on Hiro’s (1933; 1937b) original descriptions and no further specimens were examined to clarify the absence of a penis in E. squamosum. Some species of balanomorph barnacles (e.g. Semibalanus balanoides) lose the penis after the reproductive season (Barnes, 1992) but such loss has not been recorded in species of the stalked barnacle genus Pollicipes (Barnes, 1992). However, information on the relationship of the penis condition and the reproductive cycle of a large number of stalked barnacle species is still very limited (Barnes, 1992).
In the present study, we assigned the present species as Euscalpellum c.f. squamosum because the hard and soft parts of the specimens well matched with Hiro’s (1933; 1937b) descriptions. The only discrepancy between the present specimen and Hiro’s description is the absences of a penis in Hiro’s specimen. It is essential to locate and check the type specimen of E. squamosum (information and location of type specimen were not mentioned in Hiro 1933 and 1937b) and further collect samples from the type locality, to confirm the species identity of the current 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 page 27, DOI: 10.5281/zenodo.281652