Marphysa fujianensis, Wang & Li & Wang & Liang & Ji & Sun & Guo & Zhu & Wang, 2025

Marphysa fujianensis View in CoL sp. nov.

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Figures 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5

Material examined. Holotype ( MBM288249 View Materials ), coll. 27 October2021, 117°19′51.68″E, 23°41′25.11″N, subtidal, hard mud bottom, 3.8 m, Zhao’an Bay , Fujian, China. GoogleMaps

Additional material (XMU-Pol-2022-006), coll. 28October2021, 117°18′38.37″E, 23°41′5.18″N,subtidal, hard mud bottom, 2.9 m, Zhao’an Bay , Fujian, China, incomplete with only a few posterior chaetigers GoogleMaps .

Diagnosis. Prostomium strongly bilobed; eyes absent; five prostomial appendages without articulations, median antenna reaches middle of chaetiger three. Branchiae present from anterior to posterior chaetigers, with a maximum of five branchial filaments. Aciculae black or brown, sharp and translucent at distal end, with one to three in each parapodia. Supracicular chaetae include limbate chaetae, isodont pectinate chaetae with long and slender teeth (IS1), anodont pectinate chaetae with thick and large teeth (AN1), and pectinate anodont chaetae with thin teeth (AN2). Among the types of AN2, two kinds of teeth appear (short and fine, long and slender). Subacicular chaetae include compound spinigers and subacicular hooks. Subacicular hook black, unidentate with translucent tips.

Description (based on the holotype only). Holotype complete, 138 mm long with 304 chaetigers.Dark red when alive, pale when preserved ( Fig. 3A–G, K, L View FIGURE 3 ). L10 about 7.0 mm; W10 without parapodia about 3.2 mm ( Fig. 3A View FIGURE 3 ).

Prostomium strongly bilobed, with two dorso-ventrally flattened lobes separated by an anterior notch ( Fig. 3B, C View FIGURE 3 ). Anterior margin of the buccal lip rounded. Prostomium two-thirds as long as length of two peristomium rings. Five slender prostomial appendages arranged in a semicircle, with median antenna longest, reaching middle of chaetiger three. Lateral antennae shorter, reaching anterior of chaetiger three; palps shortest reaching anterior margin of chaetiger two ( Fig. 3B, D View FIGURE 3 ). Peristomium twice length of prostomium; first ring approximately three times as long as second. Ceratostyles and palpostyles tapering, slightly wrinkled. Ceratophores and palpophores ringshaped. Eyes absent.

Mandible and Maxillae brown to dark ( Fig. 3H–J View FIGURE 3 ). Mandible almost same length as Mx Ⅰ plus carriers. Mx Ⅰ approximately 2.3 times as long as carriers. Edge of Mx II serrated, with denticles on left and right sides well interlocked when maxillae close. Mx III single, arched. Mx IV paired, both attached with basal lamellae. Attachment lamella brownish-yellow with a small brown region, right Mx IV attachment lamella sickle-shaped, sclerotized, two-thirds as long as right Mx IV, and left Mx IV attachment lamella one-third as large as right attachment lamella, sclerotized. Mx V paired, flat, right one slightly smaller than left one. Maxillary formula: I = 1 + 1, II = 4 + 4, III = 4 + 0, IV = 2 + 4, V = 1 + 1.

First few parapodia located ventro-laterally and gradually becoming dorso-lateral in following chaetigers ( Fig. 3D–G View FIGURE 3 ). Dorsal cirri tapering, always longer than acicular lobes, slightly longer than ventral cirri in anterior and median chaetigers ( Fig. 4A–J View FIGURE 4 ), and similar to ventral cirri in posterior chaetigers ( Fig. 4K–O View FIGURE 4 ). From anterior to posterior chaetigers, dorsal cirri gradually becoming thinner ( Fig. 4A–O View FIGURE 4 ). Ventral cirri gradually becoming shorter from anterior to posterior chaetigers. Digitiform in approximately chaetiger 1–30, and conical in chaetigers thereafter, inflated bases not conspicuous ( Fig. 4A–O View FIGURE 4 ). Prechaetal lobe shorter than chaetal lobe throughout body. Chaetal lobe rounded in first few chaetigers ( Fig. 4A–G View FIGURE 4 ), and triangular thereafter ( Fig. 4H–O View FIGURE 4 ). Postchaetal lobe longer than chaetal lobe in anterior chaetigers, digitiform in first few chaetigers ( Fig. 4A–C View FIGURE 4 ), gradually becoming shorter and wider, and absent in posterior-most chaetigers ( Fig. 4D–O View FIGURE 4 ).

Branchiae pectinate, commencing from chaetiger 34 and extending to 18 th chaetiger previous to last chaetiger, with only a single filament in first branchiae, one to two filaments in anterior chaetigers ( Fig. 3E View FIGURE 3 ), four to five in mid-body ( Fig. 3F View FIGURE 3 ), and two to three in posterior chaetigers ( Fig. 3G View FIGURE 3 ).

Notoaciculae not observed, neuroaciculae black with pointed and paler tip, two to three per parapodia in anterior chaetigers, two per parapodia in mid-body, and one to two per parapodia in posterior chaetigers ( Figs 4A–O View FIGURE 4 ; 5M– P View FIGURE 5 ). Supra-acicular chaetae with limbate chaetae ( Fig. 5A, B View FIGURE 5 ) and pectinate chaetae ( Fig. 5D, E, G–L View FIGURE 5 ). Pectinate chaetae commencing from chaetiger two to near end. Three types of pectinate chaetae (IS1, AN1, AN2); IS1: thin, symmetrical isodont narrow with approximately 12–18 long and slender teeth, present only in anterior chaetigers ( Fig. 5D, E View FIGURE 5 ); AN1: thick, anodont wide with approximately four to five large teeth, present in posterior chaetigers ( Fig. 5J–L View FIGURE 5 ); AN2: a. thick, slightly asymmetrical, anodont wide with approximately 13–22 short and fine teeth ( Fig. 5G, H, K, L View FIGURE 5 ); b. thick, slightly asymmetrical, anodont narrow with approximately 12 long and slender teeth ( Fig. 5I View FIGURE 5 ), both present in median and posterior chaetigers. Subacicular chaetae with compound spinigers ( Fig. 5C, F View FIGURE 5 ). Two lengths of blade of compound spinigers present, number of longer one increased from anterior to posterior chaetigers. Subacicular hooks black with paler tips in anterior and median chaetigers, brown with paler tips in posterior chaetigers, emerge from chaetiger 40, one per parapodia, and unidentate throughout chaetigers ( Figs 4H–O View FIGURE 4 ; 5M View FIGURE 5 ).

Pygidium with two pairs of pygidial cirri, dorsal pair approximately 3.5 times longer than ventral pair ( Fig.3K, L View FIGURE 3 ).

Remarks. Marphysa fujianensis sp. nov., can be categorized into Group B of Marphysa by the presence of only compound spinigers and the branchiae covering most of the body ( Fauchald 1970; Glasby & Hutchings 2010). As mentioned in the introduction, there are twelve other Marphysa species of Group B originally described or recorded from the China Seas and its adjacent waters with both morphological and molecular evidence, i.e., M. digitibranchia , M. hongkongensa , M. iloiloensis , M. maxidenticulata , M. merchangensis , M. multipectinata , M. orientalis , M. setiuensis , M. tamurai , M. tribranchiata , M. tripectinata and M. victori .

Marphysa fujianensis sp. nov. (L10: 7 mm) and M. setiuensis (L10: 2.7–4.8 mm) share some characters, such as bearing only pectinate branchiae, having three types of pectinate chaetae (i.e., IS1,AN1, and AN2), and bearing black neuroaciculae in most chaetigers. However, there are differences between the two species. For example, digitiform postchaetal lobes of M. setiuensis are only present in the first three chaetigers, while in Marphysa fujianensis sp. nov., they are present in the first five chaetigers. For subacicular hooks, they are pale brown with translucent distal end in M. setiuensis , while they are black in color and present in anterior and median chaetigers in Marphysa fujianensis sp. nov. For the AN2 pectinate chaetae, Marphysa fujianensis sp. nov., has one kind with short and fine teeth ( Fig. 5G, H, K, L View FIGURE 5 ), in addition to the one with long and slender teeth ( Fig. 5I View FIGURE 5 ), while M. setiuensis only has the one with long and slender teeth ( Che Engku Abdullah et al. 2024, p. 89, Figure 12E). For the maxillary apparatuses, Marphysa fujianensis sp. nov., has fewer denticles on Mx IV (2+4) compared to M. setiuensis ((3–4)+(6–8)).

Marphysa orientalis of which the type locality is also in Fujian, China, resembles Marphysa fujianensis sp. nov., with pectinate branchiae and black neuroaciculae. These two species can be distinguished by the color of the subacicular hook, the length of postchaetal lobe, the types of pectinate chaetae, and the maximum number of branchial filaments. Marphysa orientalis has a yellow or transparent subacicular hook, while Marphysa fujianensis sp. nov., has black and brown subacicular hook. Postchaetal lobe in M. orientalis is longer than chaetal lobe throughout while in Marphysa fujianensis sp. nov., it is shorter than chaetal lobe in posterior chaetigers. M. orientalis has three types of pectinate chaetae (i.e., IS2, AN1, and AN2), while Marphysa fujianensis sp. nov., has different types (i.e., IS1, AN1, and AN2).At last, M. orientalis (L10: 13.3 mm) has a maximum of three branchial filaments, while Marphysa fujianensis sp. nov., (L10: 7 mm) has a maximum of five.

Two species, Marphysa multipectinata and M. tribranchiata , were recorded with the type locality of Taiwan, which is near Fujian, type locality of the new species. Marphysa multipectinata resembles Marphysa fujianensis sp. nov., with the types of pectinate chaetae (i.e., IS1, AN1, and AN2), but they have distinguishable characteristics. Marphysa multipectinata has yellow subacicular hooks, while Marphysa fujianensis sp. nov., has black and brown subacicular hooks; M. multipectinata has postchaetal lobe similar in size to chaetal lobe in anterior parapodia, while Marphysa fujianensis sp. nov., has postchaetal lobe longer than chaetal lobe in anterior chaetigers; M. multipectinata has palmate branchiae, while Marphysa fujianensis sp. nov., has pectinate branchiae only. Marphysa tribranchiata resembles Marphysa fujianensis sp. nov., in that they both have pectinate branchiae. However, M. tribranchiata has brown subacicular hook, while Marphysa fujianensis sp. nov., has black subacicular hook present in anterior and median chaetigers. M. tribranchiata (L10: 8.7 mm) has a maximum of three branchial filaments, while Marphysa fujianensis sp. nov. (L10: 7 mm), has a maximum number of five. Besides, the compostion of types of pectinate chaetae were different in the two species, i.e., IS1, IS2, and AN 2 in M. tribranchiata , and IS1, AN1, and AN 2 in Marphysa fujianensis sp. nov.

Seven species, i.e., Marphysa digitibranchia , M. hongkongensa , M. iloiloensis , M. maxidenticulata , M. merchangensis , M. tamurai , and M. tripectinata , are originally described from the China Seas and its adjacent waters. Marphysa fujianensis sp. nov., shares pectinate branchiae with M. hongkongensa , M. iloiloensis , M. maxidenticulata , M.merchangensis , and M. tripectinata . The color of subacicular hooks in M. hongkongensa (amber), M. maxidenticulata (pale yellow), M. merchangensis (pale brown), and M. tripectinata (brown), are different from those of Marphysa fujianensis sp. nov., which are black in anterior and median chaetigers. The types of pectinate chaetae in Marphysa maxidenticulata (IS1, IS2, and AN1), M. iloiloensis (IS1, IS2, and AN1), M. merchangensis (IS2, HE, and AN2), M. hongkongensa (IS1, IS2, AN1, and AN2), and M. tripectinata (IS2, AN1, and AN2), are different with those of Marphysa fujianensis sp. nov. (IS1, AN1, and AN2). M. tamurai has prostomium without sulcus, while Marphysa fujianensis sp. nov. has bilobed prostomium. Marphysa digitibranchia (~80 chaetigers) has two light-colored subacicular hooks per parapodium in posterior chaetiger, while Marphysa fujianensis sp. nov. (304 chaetigers) has a maximum of one subacicular hook colored in black or brown. In addition, M. digitibranchia was noted with compound subacicular hooks, which is absent in other Group B2 species.

Marphysa victori is recorded in China sea with type locality far away from China, but synonymised with M. bulla described from China, and Lavesque et al. (2020) explained that this species was likely transported to France through the oyster industry. The subacicular hooks in M. victori are transparent or pale yellow, while in Marphysa fujianensis sp. nov., they are black or brown. Marphysa victori (L10: 7.9 mm) has 2–5 neuroaciculae per parapodium, while in Marphysa fujianensis sp. nov. (L10: 7 mm), the number is 1–3.

More information about characters of all Group B2 species is listed in Supplementary Table 3.

Etymology. The specific name fujianensis is an adjective in the nominative singular, derived from the type locality Fujian Province, China. The suggested Chinese name for this species is “ā建áà”.

Habitat. Subtidal muddy sediment in coastal shallow waters.

Distribution. Marphysa fujianensis sp. nov., is currently only known from the coastal waters of Fujian Province, China.