Marphysa maxidenticulata Liu & Hutchings & Kupriyanova 2018, n. sp.
Creators: name: Liu, Yubin
name: Hutchings, Pat
name: Kupriyanova, Elena
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Eunicida
Eunicidae
Marphysa
Marphysa maxidenticulata

description: Marphysa maxidenticulata n. sp.
Figures 1, 4–6
Material examined. Holotype: AM W.49113; paratypes: MBMCAS285107, width at chaetiger 10, 4.65 mm, length to chaetiger 10, 9.4 mm, complete with 252 chaetigers; AM W.49114, width at chaetiger 10, 6.0 mm, length to chaetiger 10, 9.9 mm, complete with 307 chaetigers; AM W.49115, width at chaetiger 10, 5.6 mm, length to chaetiger 10, 10.35 mm, complete with 334 chaetigers; AM W.49116, width at chaetiger 10, 4.8 mm, length to chaetiger 10, 9.7 mm, complete with 271 chaetigers; AM W.49117, width at chaetiger 10, 4.4 mm, length to chaetiger 10, 8.95 mm, complete with 228 chaetigers. All paratypes collected intertidally from Qingdao coast (36.1°N, 120.3°E) in 2016.
Description. Holotype complete, with 232 chaetigers, regenerating posteriorly, faintly iridescent, gravid. Animal red or dark pink when alive, preserved specimen beige. Maximum width at chaetiger 10, 7.05 mm, excluding parapodia, length to chaetiger 10, 8.7 mm.
Prostomium of same length as peristomium, prostomial margins dorsally flattened with conspicuous deep median sulcus (Fig. 4A). Eyes absent. Median antenna longest and thickest prostomial appendage, inserted more posteriorly than lateral ones. Antennophores short, ring-shaped, antennal style tapering, smooth, longest reaching to median or posterior margin of second peristomium ring. Palps wrinkled, shorter than antennae. Palps slightly longer than antennae by a ratio of 1.2. Peristomial rings well demarcated all around (Fig. 4B). Jaws of paratype (AM W.49116) dissected, mandibles with white calcareous tips, longer than sclerotised matrix, with blunt pointed bases, pale brown, darker towards inside margin, 9/10 length of MxI (Fig. 4D). Maxillae I with forceps-like inflated base with deep falcal arch, maxillary carriers 3 times shorter than MxI, having inverted triangular anterior region with a pair of concave basal wings. Maxillae II with teeth pointing downwards, anterior teeth largest decreasing in size along cutting edge, dark brown, ligament between MI and MII dark rectangular. Maxillae III unpaired, forming distal arc, with short triangular teeth, largest basally. Maxillary formula: I=1+1, II=4+6, III=5+0, IV=4+7, V=1+1 (Fig. 4E).
Parapodia vary along body. Anterior parapodia with small rounded prechaetal lobe shorter than chaetal lobe, postchaetal lobe longer than chaetal lobe; postchaetal lobe elongate, digitate and 4x as long as rounded acicular lobe (Fig. 5D). Median parapodia with poorly developed preacicular lobe, acicular lobe small rounded and much shorter than rectangular postacicular lobe. Posterior parapodia with rectangular acicular lobe, postacicular lobe declining in size relative to more anterior ones and becoming globular forming small collar surrounding acicular lobe, and preacicular lobe poorly developed. Dorsal cirrus digitate throughout, in anterior and median parapodia about 0.5 times length of ventral cirrus; in posterior parapodia dorsal cirrus same length as ventral cirrus. Ventral cirrus initially bluntly triangular, becoming more squat-shaped and by mid-parapodia declining in size with small globular terminal papillae and becoming more triangular with terminal papillae. Branchiae beginning from chaetiger 28, continuing to chaetiger 212, pectinate throughout. Number of branchial filaments in anterior branchiae 1–2, maximum number of branchial filaments 3 in median parapodia (Fig. 4C). Length of branchial filaments where best developed, up to 2–2.5 times length of dorsal cirrus.
Aciculae present, black with paler tips, 2–4 per parapodia (para 10 with 4; para 50 with 4; para 90 with 4; para 90 with 4; para 130 with 3; para 170 with 3; para 210 with 2). Subacicular hooks absent from anterior parapodia, pale yellow, unidentate, starting from chaetiger 25, initially one per chaetiger, increasing to two by parapodium 103 (Fig. 5A).
Neurochaetae in two distinct bundles, supra-acicular with limbate capillaries and pectinate chaetae, subacicular with compound spinigers and falcigers and subacicular hooks. Compound spinigers arranged in two tiers of different lengths, but with smooth blades of similar width, tapering to elongate thin tips (Fig. 5C) along entire body. Number of compound spinigers within parapodium 16–35, similar variation along entire body. Compound falcigers present, restricted to anterior parapodia (Fig. 6A, B); number of compound falcigers within a parapodium 1–3, with very short blades, falcigers absent by parapodium 50. Pectinate chaetae restricted to supraacicular fascicle from parapodium 3, then on all subsequent ones (Fig. 5A, B, C, E, F). Three types of pectinate chaetae present with numbers varying 2–11 within a parapodium, variation in numbers of pectinate chaetae increases along body. Pectinate chaetae include thick asymmetrical anodont with 3–6 teeth (Fig. 5 Ca); thin symmetrical isodont with 10–12 fine teeth (Fig. 5 Eb, 5F) and thin asymmetrical with many fine teeth (Fig. 5 Cc). Chaetiger 3 with two thin symmetrical isodont with 11 or 16 teeth (Fig. 5F). Chaetiger 25 with 11 thin asymmetrical isodont with many fine teeth (Fig. 5 Cc), 2 thick asymmetrical anodont with 4 teeth (Fig. 5 Ca) and 10 thin asymmetrical isodont with 10–14 teeth (Fig. 5 Ab). Chaetiger 50 with three pectinate chaetae, all thin symmetrical isodont with numerous teeth. Chaetiger 90 with four pectinate chaetae, all thin symmetrical isodont, with numerous teeth. Chaetiger 130 with three pectinate chaetae all thin symmetrical isodont with numerous teeth. Chaetiger 153 with 10 pectinate chaetae, all thin asymmetrical isodont with either 14 or ~25 teeth. Chaetiger 170 with two types of pectinate chaetae, 3 thin symmetrical isodont with numerous teeth and one thick asymmetrical anodont with 3–4 teeth. Chaetiger 203 with two types of pectinate chaetae: nine thin asymmetrical isodont with either 14 or ~25 teeth (Fig. 5 Ec) and two thick asymmetrical anodont, with 3 or 6 teeth (Fig. 5 Ea). Chaetiger 290 with 10 pectinate chaetae, all thin asymmetrical isodont with 14 or ~25 teeth.
Simple capillary chaetae present along entire body arranged in two tiers. Number of simple capillaries within a parapodium 17–30, similar variation throughout body.
Rounded pygidium with one pair of small, smooth pygidial cirri (Fig. 3F) margins of pygidium smooth and glandular.
Variation. Among the paratypes, branchiae start from chaetigers 29 to 41, and the last 15–25 posterior-most chaetigers lack any branchiae. There is no significant relationship between the number of chaetigers and the chaetiger on which the branchiae commence (ANOVA, F=0.27, P=0.62). The maximum number of branchial filaments varies from 2 to 3, and the ratio of the length between the antennae and the palps varies between 1.1 and 1.2.
Remarks. Marphysa maxidenticulata n. sp. belongs to Group D 2 (sensu Fauchald 1970) as it has both compound spinigers and falcigers. To date, 11 species have been described, although for some details of the pectinate chaetae structure are unknown. Marphysa maxidenticulata n. sp. can be distinguished from M. angelensis Fauchald, 1970, M. chevalensis Willey,1905, and M. fallax Marion & Bobretzky, 1875 by having branchiae beginning on chaetiger 28, whereas in these three species branchiae begin more anteriorly. Another species of this group, M. languida Treadwell, 1921 has branchiae beginning from chaetiger 60 onwards. Marphysa dartevellie Monro, 1936 has spinigers restricted to the first 30 parapodia, whereas M. maxidenticulata n. sp. has spinigers present throughout the body. Marphysa maxidenticulata n. sp. can be distinguished from M. mixta Fauchald, 1970 which has thin asymmetrical anodont pectinate chaetae with 12 coarse teeth in contrast to the presence of thick asymmetrical anodont pectinate chaetae with only 3–4 teeth in the new species. Marphysa cinari Kurt-Sahin, 2014 has compound falcigers restricted to posterior parapodia and only one type of pectinate chaetae present. Marphysa sebastiana Steiner & Amaral, 2000 has bidentate subacicular hooks and only two types of pectinate chaetae, thin symmetrical isodont pectinate chaetae with ~10 teeth and thin asymmetrical isodont with ~14 teeth and lacks thick anodont pectinate chaetae so can be distinguished from M. maxidenticulata n. sp. Marphysa formosa Steiner & Amaral, 2000 also lacks thick asymmetrical anodont pectinate chaetae and has bidentate subacicular hooks, whereas unidentate hooks are present in M. maxidenticulata n. sp. Marphysa mauritanica Gillet, 1990 resembles Lysidice by having only three prostomial appendages (antennae) and no palps, but has pectinate branchiae and so it is placed in Marphysa according to WoRMS, but can easily be distinguished from M. maxidenticulata n. sp. by this character. Zanol et al. (2014) has suggested that the number of prostomial appendages is not a useful generic character. The only remaining species in this group, M. digitibranchia Hoagland, 1920 described from Hong Kong, has branchiae from chaetiger 20 and up to 5 branchial filaments unlike the new species which has branchia from chaetiger 28 and with only 1–3 filaments. No details of the presence or absence of pectinate chaetae are given by Hoagland (1920) and no information is given regarding the distribution of the compound chaetae. For all these reasons, we describe Marphysa maxidenticulata as a new species characterised by the short-bladed falcigers (Fig. 6A, B) and the presence of thick asymmetrical anodont pectinate chaetae with either 3 or 5–6 teeth.
Etymology. The specific name maxidenticulata refers to the large teeth on the pectinate chaetae, which occur along most of the body.
Habitat. Intertidal, in mud.
Type locality. Caofeidian coast, Tangshan, north China (39.13°N, 121.56°E), see Fig. 1.
description: Published as part of Liu, Yubin, Hutchings, Pat & Kupriyanova, Elena, 2018, Two new species of Marphysa Quatrefages, 1865 (Polychaeta: Eunicida: Eunicidae) from northern coast of China and redescription for Marphysa orientalis Treadwell, 1936, pp. 191-215 in Zootaxa 4377 (2) on pages 198-202, DOI: 10.11646/zootaxa.4377.2.3, http://zenodo.org/record/1163893