Acasta huangi, Yu & Kolbasov & Hosie & Lee & Chan, 2017

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), Zootaxa 4277 (2), pp. 151-198 : 164-166

publication ID	https://doi.org/ 10.11646/zootaxa.4277.2.1
publication LSID	lsid:zoobank.org:pub:9DFC7355-BA9C-43CE-9E39-8AC770624AA1
DOI	https://doi.org/10.5281/zenodo.6027903
persistent identifier	https://treatment.plazi.org/id/2B7E94CE-490F-43E1-AC1F-8DAC9E40DFF5
taxon LSID	lsid:zoobank.org:act:2B7E94CE-490F-43E1-AC1F-8DAC9E40DFF5
treatment provided by	Plazi
scientific name	Acasta huangi
status	sp. nov.

Treatment

Acasta huangi sp. nov.

Figs 11 View FIGURE 11 ̄17

Material examined. Holotype: ASIZCR000367, Longdong, Gongliao, New Taipei City, Taiwan (25°06′50.27″N, 121°55′13.40″E, water depth 17 m), July 2011, coll. J.H.Y. Yu, on host sponge Jaspis splendens (de Laubenfels, 1954) . GoogleMaps

Diagnosis. Shell white-yellow. Basis saucer-shaped, pentagonal, with 4 radial, indistinct, shallow furrows extending to crenate basal rim. Parietes with small, rare calcareous projections; sheath feeble, with horizontal striations, short internal longitudinal ribs in basal part only. Scutum with horizontal growth ridges crossed with few longitudinal ridges in lower half, latticed in upper half. Tergum with growth ridges, spur truncated, width about 1/2 of basal margin. Cirrus IV anterior ramus and basis with strong armament of curved teeth.

Description.―Shell white-yellow after extraction from sponge, becoming white after bleaching ( Figs 11 View FIGURE 11 ĀE, 12ĀL). Basis pentagonal, saucer-shaped, with 4 indistinct, shallow radial furrows extending from center of basis to tcrenated basal rim ( Fig. 12 View FIGURE 12 M, N). Parietes ( Fig. 12 View FIGURE 12 ĀL) with small, rare, external projections and fine growth lines, radii with inclined and horizontal striations, radii not reaching base; alae with strong horizontal ridges; sheath with horizontal striations, short longitudinal ribs on basal margin of parietes not reaching sheath. Inner and outer edges of alae white, thickened.

Scutum ( Fig. 11 View FIGURE 11 G, H), externally with horizontal growth ridges crossed with few longitudinal ridges resulting in only upper half being latticed, growth lines forming prominent teeth on occludent margin. Internal surface smooth, articular furrow feeble, articular ridge not prominent, about 2/3 of length of tergal margin, adductor ridge rudimentary, adductor and depressor muscle pits absent. Tergum ( Fig. 11 View FIGURE 11 I, J) with growth ridges, carinal margin perpendicular to basal margin, spur truncated, width about 1/2 of basal margin, separated from basiscutal angle, spur furrow wide, shallow, internally with scutal margin raised, crests of depressor muscles absent.

Counts of cirral segments given in Table 1. Cirrus I with rami unequal, protopod with only a few plumose setae on proximal posterior margin ( Fig. 13 View FIGURE 13 A), anterior surfaces of both rami with dense setae ( Fig. 13 View FIGURE 13 B), serrulate and bifid setae on distal ends of terminal segments of anterior and posterior rami ( Fig. 13 View FIGURE 13 C, D). Cirrus II with rami unequal, protopod anterior and posterior margins with serrulate setae ( Fig. 13 View FIGURE 13 E), distal segments of rami with bifid setae ( Fig. 13 View FIGURE 13 E, F). Cirrus III ( Fig.13 View FIGURE 13 G, H) protopod anterior and posterior margins with short and plumose setae, respectively, segments of anterior ramus without denticles, distal segments of posterior ramus with serrate and serrulate setae. Cirrus IV, rami unequal, protopod anterior and posterior margins with short and plumose setae, respectively ( Fig. 14 View FIGURE 14 A), armed with a row of 8 curved teeth on anterior margin of basis ( Fig. 14 View FIGURE 14 B), proximal segments of anterior ramus bearing 1–2 curved teeth and 1̄2 denticles on anterior margin ( Fig. 14 View FIGURE 14 C̄F), terminal segment of anterior ramus with serrulate setae ( Fig. 14 View FIGURE 14 H). Cirrus V, protopod with few short setae ( Fig. 15 View FIGURE 15 A), proximal segments of anterior ramus each bearing 1 curved tooth on anterior margin ( Fig. 15 View FIGURE 15 B̄C), distal segments of anterior ramus with serrulate setae ( Fig. 15 View FIGURE 15 D). Cirrus VI, protopod with few short setae ( Fig. 15 View FIGURE 15 E), distal segments of posterior ramus with serrulate setae ( Fig. 15 View FIGURE 15 F). Penis finely annulated, gradually tapering to tip ( Fig. 15 View FIGURE 15 G), tip with long setae ( Fig. 15 View FIGURE 15 I), basidorsal point vestigial ( Fig. 15 View FIGURE 15 H).

Maxilla bilobed, oblong ( Fig. 16 View FIGURE 16 A), distal lobe with serrulate setae ( Fig. 16 View FIGURE 16 B), outer edge without setae, inner edge straight, basal lobe with serrulate setae ( Fig. 16 View FIGURE 16 C, D). Maxillule cutting margin straight, without notch, with 9 large cuspidate setae, upper and lower pairs largest ( Fig. 16 View FIGURE 16 E, F), upper margin and lower margins with simple setae ( Fig. 16 View FIGURE 16 G, H). Mandible with 5 teeth ( Fig. 17 View FIGURE 17 A), inferior angle with 3 denticles and stout setae, lower margin bearing simple setae ( Fig. 17 View FIGURE 17 B), second tooth of mandible bifid ( Fig. 17 View FIGURE 17 C). Mandibular palp truncated ( Fig. 17 View FIGURE 17 D), outer margin concave ( Fig. 17 View FIGURE 17 E), with dense terminal setae ( Fig. 17 View FIGURE 17 F). Labrum bilobed, with V-shaped notch ( Fig. 17 View FIGURE 17 G), small tooth on each crest ( Fig. 17 View FIGURE 17 H).

Remarks. This species shares several common morphological characters of the sulcata species complex, including i) a basis with a crenate edge, ii) a truncated spur of the tergum, iii) he armament of curved teeth on the anterior rami of cirri IV and V, and iv) a rudimentary basidorsal point of the penis. However, this species can be distinguished from A. sulcata by the i) the saucer-shaped pentagonal basis, ii) a scutum with well-developed longitudinal ribs, and iii) the feeble sheath of parietes. This species is also similar to A. conica Hoek, 1913 , and A. aspera sp. nov., but differs in having short ribs along the basal margin of the parietes and a latticed pattern formed by the longitudinal striations. This species differs from A. semota Hiro, 1933 , and A. chejudoensis Kim and Kim, 1988 , as these species have a prominent articular ridge of the scutum, a narrow tergal spur, a nearly straight basal margin of the tergum, and the protopod of cirrus IV with a row of curved teeth. On the basis of these differences, the specimen is considered as a new species.

Etymology. Named in honor of Dr. Huang Yu-Sheng from National Penghu Technology University of Taiwan, a specialist in sponge diversity in Taiwan, who helped us in sponge identifications.