Patinapta deformis, Yamana & Hirashima & Sato & Yamamori, 2025

Patinapta deformis sp. nov.

[New Japanese name: Yoron-himo-ikari-namako]

( Figs 12–14 View FIGURE 12 View FIGURE 13 View FIGURE 14 ; Tables 1 View TABLE 1 , 6 View TABLE 6 , 8)

Three specimens from Yoron-jima Island were identified as new to science. We herein described the morphological characters of this new species.

Diagnosis. Total shapes of anchor plates strongly distorted, their large perforations (mostly 2–3) fewer than those of the two congener nominal species (mostly 4–7), around these few perforations, marginal area broad and flat. Basal T-shaped end of anchor ossicles large, semicircular-shape. Ciliated funnels attached at inner side body wall of right dorso-lateral interradial (IR4).

Type series. Holotype, WMNH-2015-INV-106 ; two paratypes, WMNH-2015-INV-105, 108 .

Description of holotype (of WMNH-2015-INV-106: middle-size complete specimen). External and internal morphologies as follows ( Table 1 View TABLE 1 ): 30 years-preserved specimen pale peanut color ( Fig. 12 View FIGURE 12 ). Tentacles 12, each with 10 digits of 5 pairs. On the oral-side of tentacle stem, about 10–20 sensory cups sporadically arranged in U- shape. Polian vesicle in medio-ventral position, fusiform, double ( Table 1 View TABLE 1 ), stone canal single thread-like, attached to narrow space between basal parts of tentacle ampullae at mediodorsal (IR5), suddenly turned upward and forward, resulted in vesicle facing forward, distally with mold-like madreporite. Ciliated funnels in one crowded band along midline of right dorsal interradius (IR4).

Inside body, two tufts of gonad tubules attached with both sides of anterior dorsal mesentery, also two whitish tubule organs adhered to upper and under sides of intestine canal. Intestine canal lacking loop.

Body wall coarse surface, hard and thick, sparsely scattered with ossicles, arranging latitudinal layout of all as sets of anchor and plate, their directions somewhat ordered but without symmetrical design against each axial of longitudinal muscle.

Etymology. The species name deformis , alluding to the strongly distorted anchor plate.

The present results of ossicle morphologies

Body wall ossicles anchors and anchor plates ( Fig. 13B, D View FIGURE 13 ; Table 6 View TABLE 6 ). Anchor plates ranged within 98–128 μm in length. Size of perforations noticeably variable between central area and marginal area. Largest perforation situated noticeably biased from the center, surrounded by scattering smaller perforations. Few numbers of largest perforations and several small perforations equipped with 4–18 spaced sharp-teeth arraign along with inner rim. Two calculated indicators for anchor plates and a parameter were variated within APS =0.6–22.4; Ntp =2–7; APT =11.8–20.8% ( Fig. 13 B, D View FIGURE 13 ; Table 6 View TABLE 6 ).

Anchor ossicles ranged within 144–178 μm in length ( Fig. 13 B, D View FIGURE 13 ; Table 6 View TABLE 6 ). All the anchor arms (bills) equipped with minute teeth on their outer tips, numbers of teeth variable within 2–7 (mostly 1–3 in one arm of the anchor ossicle). Anchor ossicles of this specimen had broad stem and relatively wide anchor arms, with ASW =19.1–21.3%; AEW =40.8–51.1%, and T-shaped basal end of the anchor ossicle of this species strongly widened and semicircular in shape ( Fig. 13B, D View FIGURE 13 ). Such features were have not been reported in both previously described congeneric Japanese species (both species possess crescent-like T-shaped basal end).

Body longitudinal muscle, granule ossicles of this specimen ranged within 23–36 μm in length ( Fig. 13C, E View FIGURE 13 ; Table 6 View TABLE 6 ). Calculated indicator for granule proportions was variated within GP =31.2–82.6%; GCO =44.4–77.8% and were not noticeably unbalanced between O-shaped or C-shaped granules, however some granule ossicles had one or two minute perforations, resulting in turtle-face-like characteristic shape ( Fig. 13C, E View FIGURE 13 ).

Tentacle ossicles rods, ranged within 52–85 μm in length ( Fig. 13A View FIGURE 13 ; Table 6 View TABLE 6 ). Two calculated indicators for rod proportions and complexities were variated within RP =10.7–20.3%; RC =5.1–12.2.

Observation on the morphology of calcareous ring

Calcareous plates 12, firmly bound ( Fig. 14 View FIGURE 14 ), with slight anterior projection and slight posterior depression. All radial plates perforated in each anterior half. Two ventro-lateral plates (RII; RIII) protruding strongly, and exhibit pentagonal shape, resulting in both suddenly turning sharply on these ventro-lateral plates. There is no space between the additional interradial plate (IR4’; IR3’) and adjacent radial plate (RIII; RII).

Variation of external and internal morphologies

Three specimens were all large-size specimens of about 90–120 mm ( Table 1 View TABLE 1 ), all three specimens well-matured possessing fully equipped gonad tubules in their body cavities.Their external and internal morphologies approximately agreed with each other’s ( Table 1 View TABLE 1 ).

Ossicle variation among the type series

Body wall ossicles anchors and anchor plates. Anchor plate ossicle length and calculated indicators of three specimens ranged within: 83–138 μm in length, APS =0.6–43.0, Ntp =1–6, APT =2.3–25.0%. Among these values, length, frequency of teethed perforations APT and their parameter Ntp, and non-size dependance indicator of plate skewness APS of anchor plate ossicles (both ventrally and dorsally) was not significantly different (Ps>0.05, Kruskal-Wallis’ test). From these results, the anchor plate ossicles in the body wall of the present three specimens were not different in ossicle length or the skewness of the layout for perforations. Therefore, the length (about 80–140 μm), numbers of teethed perforations (1–6), and strongly distorted (up to 43) anchor plate ossicles can be appropriate diagnostic characters.

Anchor ossicle length and calculated indicators ranged within: 144–181 μm in length, ASW =19.1–30.9%, AEW =38.2–63.8% ( Table 6 View TABLE 6 ). Among these values, lengths of anchor ossicles (both ventrally and dorsally) were not significantly different (Ps>0.05, Kruskal-Wallis’ test), while the indicator for anchor stem breadth ASW and for basal / distal ends width AEW were significantly different (Ps <0.005, Kruskal-Wallis’ test). From these results, the anchor ossicles in the body wall of the present three specimens were not different in ossicle length, but different in the shape. Therefore, proportion of the anchor ossicles can be the accurate key.

Longitudinal muscle involved both O-shaped and C-shaped granule ossicles, length and calculated indicators ranged within: 23–36 μm length, GP =31.2–82.6%, GCO =11.1–77.8% ( Table 6 View TABLE 6 ). Among these values, length of granule ossicles was not different significantly (Ps>0.05, Kruskal-Wallis’ test), also calculated indicator for proportions GP was not different significantly in GP (Ps>0.05, Kruskal-Wallis’ test, both in ventrally and dorsally), but different significantly in GCO (Ps <0.05, χ 2 -multiple test). Therefore, the length and proportion of the granule ossicles can be the appropriate keys, while the ratio C- or O-shaped granule ossicles of this species cannot be the appropriate key.

Tentacle ossicles rods, length and calculated indicators of three specimens ranged within: 35–85 μm in length, RP =10.1–26.3%, and RC =5.0–17.3. Among these values, length of rod ossicles was not significantly different (P>0.05, Kruskal-Wallis’ test), also non-size dependence indicator for proportion (RP) and non-size dependence complexities (RC) were not significantly different (Ps>0.05, Kruskal-Wallis’ test). From these results, the rod ossicles in the tentacles of the present three specimens have similar lengths, proportions and complexities. Therefore, the morphologies of the rod ossicles of this species are appropriate diagnostic characters.

Remarks

Prior specimens of this species have been misidentified as P. taiwaniensis , based on the distorted anchor plate ossicles. However, observations herein showed that all three specimens possessed ciliated funnels in their right dorsal interradius (IR4), while P. taiwaniensis possesses ciliated funnels in left dorsal interradius (IR3). Such differences are a critical morphological character (Table 7-1). Presently, genus Patinapta Heding, 1928 accommodates six species from Indo-West Pacific waters (WoRMS 2024, Table 7-1; 7-2). Four other species had been described in this genus before: P. crosslandii Heding, 1929 ; P. dumasi Cherbonnier, 1954 ; P. laevis ( Bedford, 1899) ; and Patinapta vaughani Cherbonnier, 1953 . Among these species, only P. vaughani was reported as possessing ciliated funnels in the right dorsal interradius (IR4). However, each species is distinguishable by the differences of the shapes of the longitudinal muscle granules and body wall anchor plates (Table 7-2).

Distribution

Southern Japan (Kyushu Island and the Ryukyu Islands). The present three specimens collected from intertidal sandy beach with boulders originated from dead corals, in the type locality, Yoron-jima Island, Ryukyu Islands, Kagoshima, Japan. Among the specimens housed in WMNH-INV, including the present specimens, 4 bottles including 9 specimens were identified as this species ( Table 8). Other than the type locality, 6 immature specimens collected from Yokaku bay and Hirose-gawa river mouth Amakusa City, Kumamoto, Japan were identified as this species. In both localities in Amakusa City, the specimens were collected from estuarine intertidal flats.