Marphysa tripectinata Liu, Hutchings & Sun, 2017, n. sp.
Creators: name: Liu, Yubin
name: Hutchings, Pat
name: Sun, Shichun
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Eunicida
Eunicidae
Marphysa
Marphysa tripectinata

description: Marphysa tripectinata n. sp.
Figures 1, 2, 4 H, 5A–C, Tables 2, 3
Material examined. Holotype: AM W.49069; Paratypes: AM W.49070, width at chaetiger 10, 6.2 mm, length from anterior to posterior margin of chaetiger 10, 12.7 mm, complete with 387 chaetigers; Paratypes: MBM285073, width at chaetiger 10, 6.4 mm, length from anterior to posterior margin of chaetiger 10, 12.9 mm, complete with 353 chaetigers, AM W.49071, width at chaetiger 10, 4.8 mm, length from anterior to posterior margin of chaetiger 10, 11.05 mm, complete with 378 chaetigers, MBM285074, width at chaetiger 10, 4.5 mm, length from anterior to posterior margin of chaetiger 10, 10.0 mm, complete with 416 chaetigers, AM W.49072, width at chaetiger 10, 6.3 mm, length from anterior to posterior margin of chaetiger 10, 11.25 mm, complete with 179 chaetigers.
All material purchased from bait collectors, who collected them from the intertidal along the Beihai coast (109.1608E; 21.5785N), in 2014 except for AM W.49073 which was purchased in 2015.
Additional material examined. AM W.49073, with some parapodia mounted for examination by SEM (parapodia 3, 70, 137, 204, 270, 330), complete with 338 chaetigers.
Description. Holotype complete, with 428 chaetigers. Body faintly iridescent. Animal when alive blood or deep-red in colour, preserved specimen beige. Maximum width 5.95 mm at chaetiger 10, excluding parapodia 12.7 mm in length from anterior to posterior margin of chaetiger 10.
Prostomium same length as peristomium, margins of prostomium dorsally flattened with conspicuous deep median sulcus (Fig. 2 A). Eyes absent. Antennae arranged all in straight line. Length of antennae varies, median longer and thicker than lateral ones, longest antennae reaching to chaetiger 1. Ceratophores smooth, ceratostyles tapering, smooth with slightly wrinkled surface. Palps smooth, shorter than antennae. Ratio of length between antennae and palps is 1.3 x. Peristomial rings well demarcated all around (Fig. 2 B). Mandibles with calcareous plates longer than sclerotized matrix (Fig. 2 E). Maxillae I more than twice length of carrier; teeth arrangement for maxillae II all in same plane; III arched with anterior teeth in line with posterior ones. Maxillary formula: I=1+1, II=5+5, III=5+0, IV=4+8, V=1+1 (Fig. 2 F).
Parapodia vary along the body, anterior parapodia with prechaetal lobe poorly developed and postchaetal lobe longer than chaetal lobe (chaetiger 3) by chaetiger 20 the postchaetal lobe decreasing in size and by chaetiger 95 postchaetal and chaetal lobes similar in length, prechaetal lobe small throughout. Dorsal cirri conical, longer than chaetal lobes in anterior body, posterior ones same length as chaetal lobes. Ventral cirri digitiform throughout body, the base of ventral cirri inconspicuous, length decreases in posterior body. Length of dorsal cirri and ventral cirri differ; in anterior and median chaetigers equal, in posterior chaetigers dorsal cirrus longer than ventral cirrus. Branchiae begin at chaetiger 15, and end at chaetiger 399, pectinate. Number of branchial filaments in anterior branchiae, 1–2 simple filaments, with maximum number of branchial filaments 8, in median parapodia. Length of branchial filaments where best developed up to 2–2.5x length of dorsal cirrus (Fig. 2 C–D). Parapodia 3, 20, 95, 170, 245, 320 and 395, examined under the light microscope. Aciculae black on all chaetigers, with maximum number 5, in anterior chaetigers (Fig. 2 D). Subacicular hooks present, all of same colour, brown, unidentate, present in median and posterior chaetigers always single, present from parapodia 170. Compound spinigers present, similar along entire body, with 8–25 per parapodium. Compound falcigers absent. Pectinate chaetae present, throughout, with number of pectinate chaetae within a parapodia 2–4 in anterior and 8–10 in posterior chaetigers. Pectinate chaetae of 3 types (see Table 2 for terminology), in anterior and medium parapodia, only asymmetrical isodont pectinate chaetae present with about 10 teeth. In posterior all 3 types present: asymmetrical anodont pectinate chaetae with 14–18 teeth (Fig. 2 H-(III), Fig. 4 H-VII); asymmetrical isodont pectinate chaetae with more than 30 teeth (Fig. 2 H-(1)); asymmetrical anodont pectinate chaetae with 5–7 teeth (Fig. 2 H-(II)). Limbate capillaries present throughout body, all similar, with 13–24 per parapodia.
Pygidium with 1 pair of pygidial cirri (Fig. 2 G).
Variation. The paratypes exhibit the following variation, branchiae starting from chaetigers 15 to 24, and with 11–29 of the posterior-most chaetigers without any branchiae. The maximum number of branchial filaments varies from 6–8, and Fig. 7 illustrates that there is no relationship between the segment on which the branchiae begin and the number of segments. No individuals were designated as paratypes which exhibited any signs of posterior regenerated segments. The ratio of the length between antennae and palps varies from 1.3 to 1.8.
Remarks. Marphysa tripectinata n. sp. is described as a new species because it has three types of pectinate chaetae present. Other species of Marphysa occurring in this region and lacking compound falcigers (see Table 3 which includes species belonging to Group B2, Fauchald 1970) all have either two or four types of pectinate chaetae, although for some species limited details are given with regards to the number of teeth present. The majority of the species in Table 3, have only asymmetrical pectinate chaetae similar to M. tripectinata n. sp. although M. macintoshi Crossland, 1903, M. teretiuscula (Schmarda, 1861) and M. tribranchiata n. sp. only have symmetrical ones. Marphysa tripectinata n. sp. shares with all of the species in Table 3, branchiae continuing almost to the posterior end with considerable variation in the segment on which they begin (Fig. 7). Zanol et al. (2016) discussed the variation of this character found in M. mullawa Hutchings & Karageorgopoulis, 2003. One of the major distinguishing characters of M. tripectinata n. sp. is the very late appearance of subacicular hooks around parapodia 170, whereas in other species in this group they occur much earlier on the anterior part of the body (see Table 2). Although Glasby & Hutchings (2010) indicated that the segment on which subacicular hooks first occur is related to size, the very late appearance in M. tripectinata n. sp. is different from all other species in this group. The late appearance of subacicular hooks, types of pectinate chaetae present and the large number of branchial filaments in medial parapodia distinguishes it from other species recorded from China (see Table 3) and are important diagnostic characters and therefore we describe it as a new species.
Etymology. The specific name tripectinata refers to the presence of three types of pectinate chaetae present.
Habitat. Intertidal
Type locality. Beihai coast, south of China, (109.1608E; 21.5785N), see Fig. 1.
description: Published as part of Liu, Yubin, Hutchings, Pat & Sun, Shichun, 2017, Three new species of Marphysa Quatrefages, 1865 (Polychaeta: Eunicida: Eunicidae) from the south coast of China and redescription of Marphysa sinensis Monro, 1934, pp. 228-250 in Zootaxa 4263 (2) on pages 232-234, DOI: 10.11646/zootaxa.4263.2.2, http://zenodo.org/record/573070