Fibularia japonica Shigei, 1982

Tanaka, Hayate, Wakabayashi, Kaori & Fujita, Toshihiko, 2019, A new species of Fibularia from Japanese waters with a redescription of F. japonica and F. ovulum (Echinodermata: Echinoidea: Clypeasteroida), Zootaxa 4543 (2), pp. 241-260 : 252-257

publication ID	https://doi.org/ 10.11646/zootaxa.4543.2.4
publication LSID	lsid:zoobank.org:pub:2A1736C7-FB28-4C8E-9954-B17BA60B6E57
DOI	https://doi.org/10.5281/zenodo.4562873
persistent identifier	https://treatment.plazi.org/id/6B335535-DD28-0D33-FF4B-BECAC2830858
treatment provided by	Plazi
scientific name	Fibularia japonica Shigei, 1982
status

Treatment

[Japanese name: Nihon mame-uni (named by Shigei 1986)]

Figs. 4 View FIGURE 4 , 6 View FIGURE 6 , 9–13 View FIGURE 9 View FIGURE 10 View FIGURE 11 View FIGURE 12 View FIGURE 13 ; Tables 1 View TABLE 1 , 2 View TABLE 2 ; Electronic Supplementary Table S1 View TABLE 1 .

Fibularia sp. nov.— Shigei 1981: 202 (probably part).

Fibularia japonica Shigei, 1982: 11 –16, figs. 1–48 (part).

Fibularia japonica Shigei 1986: 116 –117, Pl. 92, figs. 4–9; Schultz 2005: 321, fig. 602; Shigei 2006: 318 –319; Yoshigou 2009: 35 –36, pl. 1, fig. 4; Gomez & Mooi 2015: poster presentation.

Material examined. Holotype: 1 specimen, UMUTZ-Ecn-SG10-16T , denuded test, off Misaki Marine Biological Station , Sagami Bay, sublittoral zone, coll. K. Aoki, J. Deguchi, T. Sekimoto, H. Suzuki, and M. Shigei, 1926– 1978 . Paratypes: 1 specimen, UMUTZ-Ecn-SG10-18T, dead test, 3 km off Futamachiya , Sagami Bay (35°08.5′N, 139°35.0′E), depth 45 m, coll. H. Suzuki, M. Sekimoto, K. Shimazaki, and M. Shigei, 4 Jul. 1979 GoogleMaps ; 6 specimens, UMUTZ-Ecn-SG10-17T No. 2–6, 8, dead tests, off Misaki Marine Biological Station , Sagami Bay, sublittoral zone, coll. K. Aoki, J. Deguchi, T. Sekimoto, H. Suzuki, and M. Shigei, 1926–1978 ; 1 specimen, UMUTZ-Ecn-SG10-19T, dead test, Tomioka , Amakusa group, Kumamoto Prefecture, Japan, depth 30 m, coll. T. Kikuchi, 14 Feb. 1963 ; 26 specimens, UMUTZ-Ecn-SG10-20T, dead tests, Sagami Bay , sublittoral zone ; 3 specimens, UMUTZ-Ecn-SG10-21T, dead tests, Sagami Bay , sublittoral zone ; 1 specimen, UMUTZ-Ecn-SG10-22T, dead test, Suruga Bay , sublittoral zone, coll. Y. Okada.

Non-type specimens: 45 specimens, NSMT E-10389, dead tests, Sagami Bay (35°09′18″N, 139°35′12″E), depth 74.1 m, dredging, coll. H. Tanaka, 23 Jan. 2014 GoogleMaps ; 6 specimens, NSMT E-10390, whole, denuded, SEM stub, Sagami Bay (35°09′18″N, 139°35′13″E), depth 74.1 m, dredging, coll. H. Tanaka, 23 Jan. 2014 GoogleMaps ; 15 specimens, NSMT E-10391, dead tests, Sagami Bay (35°08′09″N, 139°34′47″E), depth 87.5–88.6 m, dredging, coll. S. Teruya, 14 Mar. 2012 GoogleMaps .

One paratype specimen (UMUTZ-Ecn-SG10-17T No. 7) was identified as F. coffea in this study.

GenBank accession number. LC388936 View Materials (non-type specimen: NSMT E-10390, Sagami Bay , Japan)

Emended diagnosis. Test outline elliptical when viewed from above; height low; oral surface not depressed. Periproct outline round to oblong. Petaloid region large; number of pores in petal III up to 14 even in the specimens of TL> 7.5 mm. Diameter of genital pores equal to or larger than that of petaloid pores in mature individuals. Two hydropores opening in an irregularly-shaped groove. Black pigments not forming symmetric pentaradial in living animals. Spatula-like primary spines around periproct.

Description. The test is very small (TL = 2.19–9.70 mm) ( Fig. 9 View FIGURE 9 ), flattened (TH/TL = 0.49–0.80) ( Fig. 9C View FIGURE 9 ), and elliptical when viewed from above (TW/TL = 0.67–0.83) ( Figs. 9A, B View FIGURE 9 ). The test proportion hardly changes with the test growth (slope value is 1.0 between TW and TL, as well as between TH and TL in the allometry regression; Table 1 View TABLE 1 ). The oral surface is flattened. The aboral surface is slightly arched convex. There are no internal buttresses. Food grooves are absent ( Fig. 9B View FIGURE 9 ). The ambulacra are almost the same width as the interambulacra ( Fig. 9 View FIGURE 9 G–I). The height of both ambulacral and interambulacral plates are lower than the width at the ambitus ( Fig. 9I View FIGURE 9 ). The petaloid region is large (PL/TL = 0.33–0.66, PW/TW = 0.28–0.51). The ratio of petaloid size to test size increases with the test grows (slope value is 1.1 between PL and TL, as well as between PW and TL in the allometry regression). Each petal is composed of two almost parallel series of pore pairs lying oblique, and crossing the ambulacral plates ( Fig. 9G View FIGURE 9 ). The number of pores of petal III, IV, and V increases up to 14, 12, and 14, respectively, before reaching TL = ca. 3 mm, and hardly increases after that size has been reached ( Fig. 4 View FIGURE 4 ). The pores become larger towards the distal tip of the petals.

The peristome, situated at the anterior-posterior midpoint of the oral side, is small (SL/TL = 0.13–0.27, SW/ TW = 0.12–0.25) and slightly elongated antero-posteriorly ( Figs. 9B, E, H View FIGURE 9 ). The ratio of peristome size to test size becomes smaller with the test grows (slope value is 0.7 between SL and TL, as well as between SW and TL in the allometry regression). Two buccal pores are situated in each ambulacrum at the edge of the peristome. Single sphaeridium is fully enclosed within the test, and in the sphaeridial chamber in each ambulacrum near the peristome.

The round to oblong shaped periproct is located halfway between the peristome and posterior margin of the test and is smaller than the peristome (AL/TL = 0.09–0.15, AW/TW = 0.09–0.16) ( Figs. 9B, E, H View FIGURE 9 ), and covered by 4–6 (usually 5) naked radiating periproctal plates. The ratio of periproct size to test size becomes smaller with the test grows (slope value is 1.0 between AL and TL, and 0.8 between AW and TL in the allometry regression).

The apical system is situated slightly anteriorly on the aboral surface ( Figs. 9A, D, G View FIGURE 9 ). It consists of four genital pores, five ocular pores in small ocular plates, and two hydropores in a deep, irregularly-shaped groove ( Figs. 10A, B View FIGURE 10 ). The diameter of the genital pores (<323 µm) is equal to or larger than that of the largest petaloid pores (<ca. 200 µm) ( Figs. 10A, B View FIGURE 10 ). There is a clear dimorphism in gonopore size ( Fig. 6 View FIGURE 6 ). The gonopores open in specimens as small as TL = 3.48 mm. The diameter of the ocular pores (ca. 40 µm) is much larger than that of the accessory pores (ca. 25 µm). Accessory pores are situated in oblique patches in the centers of ambulacral plates ( Fig. 10C View FIGURE 10 ).

The primary tubercles are hemispherical, crenulate, and perforate ( Fig. 10D View FIGURE 10 ). The diameters of oral and aboral primary tubercles are almost equal, ca. 150–200 µm. Their mamelons are constricted at the base. The miliary tubercles are hemispherical, poorly to non-crenulate, and indistinctly to non-perforate ( Fig. 10D View FIGURE 10 ). They scattered around the primary tubercles. The diameters of oral and aboral miliary tubercles are almost equal, ca. 50–60 µm. The glassy tubercles occur between primary and miliary tubercles ( Fig. 10D View FIGURE 10 ).

The primary spines are ca. 350–450 µm in length ( Fig. 11 View FIGURE 11 Ai). The number of wedges in a primary spine is 8– 10, and each wedge has many small granules and a series of distinct denticles ( Figs. 11 View FIGURE 11 Aii, Aiii). The primary spines around the peristome are slightly curved at their ends towards the peristome, and their shafts are somewhat broadened and flattened ( Fig. 11B View FIGURE 11 ). Approximately 10–20 primary spines in the region posterior to the periproct ( Fig. 12A View FIGURE 12 ) are slightly shorter than the other primary spines. Distally, these spines are slightly flattened and bent over like a spatula ( Fig. 12C View FIGURE 12 ) towards the anterior of the animal ( Figs. 12A, B View FIGURE 12 ). The miliary spines are ca. 250–350 µm in length ( Fig. 11 View FIGURE 11 Ci). Each miliary spine has a terminal crown ( Fig. 11 View FIGURE 11 Cii) and the number of wedges in a miliary spine is six. Each wedge has many small granules along its outer surface ( Fig. 11 View FIGURE 11 Ciii).

Two types of pedicellariae, ophicephalous and tridentate, are present ( Figs. 11D, E View FIGURE 11 ). These three types pedicellariae occur on small tubercles similar to those of miliary spines. The ophicephalous pedicellariae ( Fig. 11D View FIGURE 11 ) are numerous and occur over the entire test surface. The head is ca. 80–100 µm in length ( Fig. 11 View FIGURE 11 Di), and consists of three valves that differ from each other in size and shape. The largest valve has a large, bilaterally symmetric handle. The medium-sized valve has a left-right asymmetric handle. The smallest valve has a small, bilaterally symmetric handle. Each valve has “intertwined loop” as described for F. coffea . Each valve has 20–25 teeth, and each tooth has 1–2 denticles. The proximal end of the handle on the largest valve is inserted into a depression at the distal end of the pedicellarial stalk ( Fig. 11 View FIGURE 11 Dii).

The tridentate pedicellariae ( Fig. 11E View FIGURE 11 ) occur only around the peristome and periproct. These pedicellariae consist of a head with three slender valves ( Fig. 11 View FIGURE 11 Ei), short neck, and stem. The valves possess ca. 11–20 teeth on the edge and without denticles ( Fig. 11E View FIGURE 11 ). Some valves have ca. 1–4 teeth in the inner area ( Fig. 11 View FIGURE 11 Eiv).

The accessory tube feet lack a calcareous disk or spicules.

Color. The color is white to yellow in life ( Fig. 13A View FIGURE 13 ) but changes to green when preserved in ethanol. Black pigments are distributed in speckles over the entire test ( Fig. 13B View FIGURE 13 ) and remain even after preservation. The denuded test is whitish.

Distribution. F. japonica has so far been recorded in Japanese waters, from Sagami Bay to Kyushu; 30–100 m in depth ( Shigei 1986; present study). Schultz (2009) reported this species from also the Philippines.

Habitat. Live specimens collected from sandy bottoms by dredging suggest that F. japonica inhabits sandy substrate.

Remarks. In the original description of F. japonica, Shigei (1982) noted that “each pore series of petals consists of only 2–3 pore pairs in adult specimens, while 4–5 in young specimens [sic].” His statement that the number of pores decreases with growth is erroneous because it always increases with growth in clypeasteroids ( Zachos 2015) and all other echinoids. As a result of the re-examination of the type specimens of F. japonica , one of the paratypes (UMUTZ-Ecn-SG10-17T No. 7) showed the morphology of F. coffea . This paratype specimen is 4.11 mm in TL, has five pore pairs in each pore series (total 20 pores) in petal III (x-mark in Fig. 4 View FIGURE 4 ). We confirmed that the number of pores in petal III does not exceed 15 in any of the paratypes of F. japonica . We assumed that this relatively small specimen of F. coffea , mixed in the type specimens of F. japonica , caused his strange statement in the original description ( Shigei 1982). True F. japonica is a species with less than 4 pore pairs in each pore series (a total of max. 16 pores per petal).

Shigei (1982) described a valve of ophicephalous pedicellariae that had no trace of intertwined loops ( Shigei 1982: fig. 48). However, we observed that the valves of ophicephalous pedicellariae of F. japonica are characterized by well-developed intertwined loops ( Fig. 11 View FIGURE 11 Di). Therefore, the valves of an ophicephalous pedicellaria do not separate from each other even after the soft tissues are removed by bleaching. The valve suggested to be from an ophicephalous pedicellaria illustrated by Shigei (1982: fig. 48) is more similar to that of a tridentate pedicellaria ( Fig. 11E View FIGURE 11 ), suggesting that Shigei mislabeled the valve in his illustration.