Euscalpellum Hoek, 1907

Young, Paulo S., 2002, Revision of the Scalpellidae (Crustacea, Cirripedia) in the collection of the Muséum national d’Histoire naturelle, France, studied by Abel Gruvel, Zoosystema 24 (2), pp. 309-345 : 311-315

Genus Euscalpellum Hoek, 1907

Euscalpellum renei (Gruvel, 1902) ( Figs 1-3 )

Scalpellum renei Gruvel, 1902c: 229 , pl. 12, figs 5-7; 1902d: 523; 1905: 39, fig. 38. — Schmalz 1906: 67.

Scalpellum (Smilium) renei – Pilsbry 1907: 13.

Euscalpellum renei – Pilsbry 1908: 108. — Krüger 1911: 17. — Joleaud 1916: 39. — Withers 1953: 171. — Zevina 1978a: 1001; 1981a: 86, fig. 57. — Young 1995: 244.

Smilium renei – Bassindale 1961: 485. — Stubbings 1961a: 9, fig. 1; 1961b: 181; 1967: 233.

TYPE MATERIAL. — Angola. Saint-Paul-de-Loanda, 1886, Cavelier de Cunerville leg., lectotype by present designation, rc (tl) 2.6 (3.6) mm ( MNHN Ci 373) ; paralectotypes 3 spec., cl (tl) 1.2 (1.4) to 3.4 (4.4) mm ( MNHN Ci 373) .

MATERIAL EXAMINED. — Golf of Guinea, Calypso , stn 19, 5°2’90”N, 5°24’40”W, 21-27 m, 1956, 1 spec., cl (tl) 5.4 (7.1) mm ( MNHN Ci 374). Hermaphrodite without males. The body was dissect- ed, with the appendages mounted on slides.

DIAGNOSIS. — Capitulum with 15 plates, distributed in three rows; all plates without apical umbo except tergum.

DESCRIPTION

Hermaphrodite. Capitulum ( Fig. 1A, B ) with 15 plates, covered by hairless cuticle; length a little larger than twice width; carinal margin bent, basal portion straight, distal portion concave, occludent margin concave. Plates thin, nearly smooth, with thin growth lines. Plates separated from each other by cuticle.

Scutum ( Fig. 1B ) approximately quadrangular, with umbo a little above middle of occludent margin; length more than twice its width; occludent and lateral margins nearly straight, tergal and basal margins concave.

Tergum ( Fig. 1B ) elongate, apex blunt, curved to carina; occludent and carinal margins convex, basal margin mostly convex, but with a concavity near upper portion of scutum; surface area larger as that of scutum; three apico-basal ridges at occludent surface.

Carina ( Fig. 1B, D ) bent, basal portion straight, upper portion curving upward, umbo at two thirds of length, tectum uniformly convex, basal margin rounded.

Upper-latus (L1) ( Fig. 1B ) flat, pentagonal, higher than wide, slightly wider apically than basally; all margins almost straight; carinal margin longest, followed by inframedian-lateral margin, and tergal and scutal margins which have equal length, basal smallest; length of plate about half length of scutum; umbo central not projected.

Inframedian-latus ( Fig. 1B ) flat, displaced from lower whorl, situated higher than that of the other laterals, quadrangular, equilateral, all margins straight; umbo central, not projected.

Plates of the lower whorl convex with irregular shape. Rostrum ( Fig. 1B, C ) large; half the length of scutum; situated as high as carino-latus and higher than other in lower whorl plates; in lateral view, uniformly curved toward scuta; in rostral view, nearly quadrangular, with medio-apical umbo projected.

Rostro-latus ( Fig. 1B ) large, irregularly shaped, all margins straight except by rostral, which is undulated; umbo nearly central, projected outwards.

Carino-latus ( Fig. 1B ) elongated, with umbo medio-basal, projected, much higher than wide and wider above umbo.

Sub-carina ( Fig. 1B, D ) in lateral view triangular, in carinal view pentagonal, with umbo nearly central, all margins concave.

Peduncle ( Fig. 1B ) short, about one third of capitulum length. Cuticle thick, with several small conic scales well embedded in cuticle, with apparently no organization.

Prosoma ( Fig. 2A ) with four filamentary appendages along dorsal midline, one anteriorly and others together, all with almost same length. Labrum ( Fig. 2B ) bullate, crest with scattered denticles. Palp ( Fig. 2B ) small, paddle-like, simple setae along the inner margin and distal portion. Mandible ( Fig. 2C ) with four large teeth, second to fourth with upper margin denticulate, and a small pointed tooth on lower angle; distance between first and second tooth twice that between second and third. Maxilla I ( Fig. 2D ) with cutting edge with a small notch on upper portion and slightly projected below; upper portion with two large and strong and three median setae above notch, and five median spines bellow notch, and two large and 10 thin setae on projected portion. Maxilla II ( Fig. 2E ) slightly bilobed, with simple and finely pinnate setae along margins, except in the notch; papilla of maxillary gland not pronounced.

Cirrus I ( Fig. 3A ) situated far apart from the cirrus II, with rami of almost same length; articles clothed with numerous, simple and finely pinnate setae. Cirri II-VI with equal rami; intermediate articles of cirrus VI ( Fig. 3B ) three times as long as wide, armed with four pairs of long setae and setulae at the base of long setae, all setae simple, two setae on posterior angle. Setal-article ratio about 5:1. Caudal appendage leaf-like ( Fig. 3C ), unarticulated, with a constriction near base, short, smaller than protopodite, with several setulae along anterior margin and apex and one long, thin, distal seta. Penis ( Fig. 3C ) short, a little larger than protopodite, clothed by small setae. Males absent. Number of articles of cirri I- VI is presented in Table 1.

REMARKS

The type series contains very small specimens, mostly decalcified, with most characters difficult to observe. The description above is based on the specimens collected by La Calypso .

Gruvel (1902c) described this species based on three very small specimens (capitular length varying between 1.2 and 3.4 mm). The present description is based on one specimen from Guinea Gulf with 5.4 mm of capitular length, which was studied previously by Stubbings (1961b).

Euscalpellum encompasses six species, characterized by the presence of 15 plates on capitulum arranged in three rows. Of these species, only E. renei and E. rostratum (Darwin, 1852) have the capitular plates with umbo not apical, except the tergum and rostrum in E. rostratum . But the shape and umbo position of the other capitular plates clearly distinguish E. renei from E. rostratum . Otherwise, E. rostratum has an Indo-west Pacific distribution and E. renei is known only from the tropical west coast of Africa. E. renei is recorded from Guinea ( French Guinea) to Angola (11°N to 9°S) from 21-27 to 63 m. It was collected on tubes of polychaetes and hydroids.

Figures

FIG. 1. — Euscalpellum renei (Gruvel, 1902); A, lectotype (MNHN Ci 373), left lateral view; B-D, La Calypso (MNHN Ci 374); B, left lateral view; C, rostral view; D, carinal view. Scale bars: 1 mm.

FIG. 2. — Euscalpellum renei (Gruvel, 1902), La Calypso (MNHN Ci 374); A, prosoma with filamentary appendages; B, labrum and palp; C, mandible; D, maxilla I; E, maxilla II. Scale bars: A, 1 mm; B-E, 0.1 mm.

FIG. 3. — Euscalpellum renei (Gruvel, 1902), La Calypso (MNHN Ci 374); A, cirrus I; B, median article of cirrus VI; C, protopodite of cirrus VI, caudal appendage and penis. Scale bars: 0.2 mm.