Acasta sulcata Lamarck 1818
Creators: name: Yu, Meng-Chen
name: Kolbasov, Gregory A.
name: Hosie, Andrew M.
name: Lee, Tse-Min
name: Chan, Benny K. K.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Maxillopoda
Sessilia
Archaeobalanidae
Acasta
Acasta sulcata

description: Acasta sulcata Lamarck, 1818
Figs 25 ̄31
Acasta sulcata Lamarck, 1818: 668.― Deshayes 1831: 24, fig. 24.― Darwin 1854: 310 ̅311, pl. 9, fig. 2a̅2d.― Borradaile 1903: 442.― Gruvel 1905: 263 ̅264, fig. 294.― Krüger 1911: 56, tab. 1, fig. 9; tab. 4, fig. 40.― Hoek 1913: 233.― Pilsbry 1916: 241.— Hiro 1937a: 451 ̅454, figs 31, 32.― Broch 1947: 6.― Kolosváry 1947: 361.― Utinomi 1958: 309.― Newman and Ross 1976: 54.― Foster 1980: 207 ̅232, tab. 3, fig. 4A.― Ren 1984: 191 ̅193, fig. 5, tab. 3, figs 1̅9.— Jones 1990a: 222, fig. 12.— Jones 1990b: 400, fig. 23. ― Kolbasov 1993: 411, fig. 10.― Liu and Ren 2007: 423 ̅425, fig. 192.― Biccard 2012: 93, pl. 23, figs E, F.
Acasta sulcata anchoris Barnard, 1924: 81, pl. 1, fig. 16.
Acasta serrata Hiro, 1937b: 64 –66 fig. 12.
Acasta sulcata spinosa Daniel, 1956: 29 ̅30, pl. 8, figs 7̅14.
Material examined. ASIZCR000369, Daping, Yeliou, Wanli, Taiwan (25°12′45.18″N, 121°42′04.29″E, water depth 18̄ 26 m), August 2011, coll. B.K.K. Chan, on host sponge Callyspongia sp.
CEL-SN48-3 data same as for ASIZCR000369.
Diagnosis. Shell white to pale yellow, orifice rather small, with toothed edge. Basis saucer- or cup-shaped, pointed towards central umbo, rim crenate. Shell in adults often with membrane-covered clefts between plates. Externally, scutum with horizontal growth ridges, articular furrow shallow. Spur of tergum broad, square shaped, truncated at end, width slightly more than 1/2 of basal margin. Sheath extending approximately half of parietes, with internal vesicular structure, inner shell surface below sheath with longitudinal ribs. Proximal segments of anterior ramus and basis of cirrus IV with curved teeth.
Description. Shell (Figs 25, 26) white to pale yellow after extraction from sponge, becoming white (sometimes tinged with reddish patches towards apex) after bleach treatment, orifice rather small, toothed; basis saucer- or cup-shaped, rim strongly crenated. Membrane covered clefts between junctions of parietes often present. Parietes externally smooth, with horizontal growth ridges and few calcareous projections, radii with inclined and horizontal striations; parietes internally ribbed, apices incurved, sheath extending over half of parietes, with vesicular structure, radii and alae with horizontal ridges, both not reaching base; inner and outer edges of alae white, thickened; carinolaterals narrow, about 1/6 of width of laterals (Figs 25 ĀC, 26ĀL).
Externally, scutum with horizontal growth ridges, without longitudinal striation; 11̄13 teeth on occludent margin, tooth size increasing gradually from apex to base; basal margin slightly concave in middle; articular furrow shallow, articular ridge low, not prominent, not truncated, about ½ of tergal margin; adductor ridge and pit of adductor muscle feebly developed; pit of depressor muscle rudimentary (Fig. 25 F, G).
Tergum thin, semitransparent; apex beaked; articular ridge short; spur broad, separated from basiscutal angle, truncated, square-shaped, width exceeding 1/2 of basal margin, spur furrow shallow, wide; internally, scutal margin slightly raised, carinal margin perpendicular to basal margin, depressor muscle crests absent (Fig. 25 H, I).
Counts of cirral segments given in Table 1. Cirrus I, rami unequal (Fig. 27 A), protopod anterior margin lacking setae, posterior margin with serrulate and plumose setae (Fig. 27 B), thick serrulate setae on posterior margins of both rami (Fig. 27 C), serrulate and bifid setae on distal margins of terminal segments of anterior ramus and posterior ramus (Fig. 27 D, E). Cirrus II, rami unequal, protopod anterior and posterior margins with pappose and plumose setae, respectively (Fig. 27 F), thick serrulate setae on posterodistal angle of segments of both rami (Fig. 27 G), distal segments of anterior and posterior rami with bifid and serrulate setae (Fig. 27 H, I). Cirrus III, rami subequal, protopod anterior and posterior margins with simple and plumose setae, respectively (Fig. 28 A), serrulate setae along segments (Fig. 28 B), terminal segments of anterior and posterior rami with serrate and serrulate setae (Fig. 28 C, D). Cirrus IV, rami unequal, protopod anterior and posterior margins with simple and plumose setae, respectively (Fig. 28 E), armed with 12 teeth (acute and truncate) on anterior margin of basis (Fig. 28 F), frontal edge of proximal and intermediate segments of anterior ramus bearing 3 or 4 teeth (acute and truncate) (Fig. 28 ḠI), intermediate segments with 3 pairs of long simple similar length setae (Fig. 28 I), terminal segment of anterior and posterior rami with serrate setae (Fig. 28 J). Cirri V and VI similar, rami subequal, protopod anterior and posterior margins with serrulate and short simple setae, respectively, intermediate segments of rami with 2 pairs long serrulate setae, terminal segments of anterior and posterior rami with serrate setae (Fig. 29 ĀG). Cirrus V bearing 1 or 2 small teeth at frontal edge of proximal segments of anterior ramus (Fig. 29 C, D).
Penis finely annulated, gradually tapering to tip (Fig. 30 H), basidorsal point vestigial (Fig. 29 J), distal tip with long setae (Fig. 29 I).
Maxilla bilobed (Fig. 30 A), inner edge straight, distal end with thick serrulate setae (Fig. 30 B̄D); outer edge with simple setae, basal portion without setae (Fig. 30 B). Maxillule cutting edge straight without notch, with 11 large, cuspidate setae (Fig. 30 E, F), upper margin with 7 or 8 pairs of simple setae (Fig. 30 G), lower margin with numerous simple setae (Fig. 30 H). Mandible with 5 teeth, second to fourth bifid, inferior angle blunt with stout, simple setae (Fig. 31 A, B), upper margin of lateral angle bearsing simple setae (Fig. 31 C, D). Mandibular palp broadly truncated (Fig. 31 ĒH), dense serrulate setae terminally and at outer margin (Fig. 31 E, F), middle region of outer margin concave (Fig. 31 G). Labrum bilobed, separated by V-shaped notch, 3 small teeth on each side of crest (Fig. 31 I, J).
Remarks. Morphological characters of our specimens are consistent among the samples collected. Previously, numerous brief descriptions and records of A. sulcata have been provided, but these most likely represent a complex of cryptic species (see Introduction). Even among specimens assigned by Darwin (1854) to his var. a, considerable variation was noted; for example, hooked teeth may or may not be present on the segments and protopod of cirrus IV. Hiro (1937a) described specimens having a recurved tooth on the median segments of the anterior ramus of cirrus V, which are notably lacking in the present specimens as well as in Darwin’s varieties (Darwin 1854). Our specimens fit the morphology of A. sulcata var. b of Darwin (1854) because of the presence of externally smooth and internally ribbed parietes, with membrane-covered clefts in the shell plates, which are also not mentioned by Hiro (1937a).
The present specimens were extracted from a species of Callyspongia and represent only the second attempt at identifying the host. The first attempt was by Kolbasov (1993), who listed the hosts as belonging to the genus Haliclona and a member of the Myxillidae. Host utilization and specificity is a poorly explored area of sponge–barnacle diversity.
The re-examination of specimens and hosts described in the literature as well as the use of molecular data from recent collections are essential for understanding what constitutes intra- or inter-specific variation. The status of Lamarck’s (1818) and Darwin’s (1854) specimens is currently unknown.
description: Published as part of Yu, Meng-Chen, Kolbasov, Gregory A., Hosie, Andrew M., Lee, Tse-Min & Chan, Benny K. K., 2017, Descriptions of four new sponge-inhabiting barnacles (Thoracica: Archaeobalanidae: Acastinae), pp. 151-198 in Zootaxa 4277 (2) on pages 179-187, DOI: 10.11646/zootaxa.4277.2.1, http://zenodo.org/record/809554