Composetia budaiensis, Hsueh, 2018

Hsueh, Pan-Wen, 2018, First records of Composetia, Eunereis and Nectoneanthes (Annelida: Nereididae) from Taiwan, with descriptions of two new species, Zootaxa 4531 (2), pp. 211-224 : 212-216

Composetia budaiensis n. sp.

Figs 1 A–C, 2A–D, 3A–H

Material examined. Holotype ( NMNS 7898-001 ), Budai (23°19´33˝N 120°07´35˝E), Chiayi County, intertidal mudflat, 7 January 2007 . Paratypes: 5 specimens ( NMNS 7898-002 – 006 ), collection information same as holotype .

Diagnosis. Body nereidid form, longest posterior tentacular cirri reaching chaetiger 4 to 5. Two pairs of eyes, trapezoidal arranged. Jaws light brownish, each with 7 lateral teeth; conical paragnaths on maxillary ring of pharynx as: Area I=2–5; Area II=7–10 (left), 7–10 (right); Area III=17–27; Area IV=6–12 (left), 6–9 (right); oral ring without paragnaths. Notopodial prechaetal lobe present from chaetiger 3 to posterior chaetigers. Notochaetae: homogomph spinigers. Neurochaetae, dorsal fascicle: homogomph and sesquigomph spinigers. Neurochaetae, ventral fascicle: homogomph and sesquigomph spinigers on anterior chaetigers; homogomph and sesquigomph spinigers, long sesquigomph falcigers on posterior chaetigers.

Description. Holotype, incomplete, posterior body missing, remaining body length 34.0 mm with 47 chaetigers, maximum width 1.6 mm at chaetiger 6, excluding parapodia; beige in alcohol ( Fig. 1A ).

Prostomium anterior margin entire, one pair of antennae arising anteriorly, one pairs of biarticulated palps with conical palpostyles; four pairs of tentacular cirri, longest posterior cirri reaching chaetiger 5 (chaetiger 3–4, n=5). Two pairs of eyes, anterior and posterior pairs similar in size, trapezoidal arranged. Apodous segment present, about 1.1 times as long as chaetiger 1. Pharynx with light brownish jaws, each with seven lateral teeth; conical paragnaths on pharyngeal maxillary ring as: Area I=2 (2–5, n=3; sample size of Area II, III & IV same as Area I), in a transverse row (when 5, in 2 transverse rows); Area II=9 (7–10) (left), 8 (7–10) (right), in a cluster (or in a crescentic line) ( Fig. 1B ); Area III=20 (17–27), in 2 (3) transverse rows; Area IV=6 (6–12) (left), 7 (6–9) (right), in a cluster ( Fig. 1C ); oral ring of pharynx without paragnaths ( Fig. 1B, C ).

First 2 chaetigers with neuroaciculae only, thereafter noto-aciculae also present. Notopodial dorsal ligule triangular with distal tapering, base slightly expanded dorsally on anterior chaetigers ( Fig. 2A, B ); basal dorsal edge of dorsal ligule filled with glands on anterior chaetigers and entire dorsal ligules filled with gland on posterior chaetigers ( Fig. 2 A–D). Notopodial ventral ligule triangular with distal tapering on anterior chaetigers, less developed on posterior chaetigers ( Fig. 2 A–D). Dorsal cirri attached basally to dorsal ligule ( Fig. 2 A–D), about as long as dorsal ligule on anterior chaetigers ( Fig. 2A, B ), becoming shorter than dorsal ligule on posterior chaetigers ( Fig. 2C, D ). Notopodial prechaetal lobes present from chaetiger 3 to posterior chaetigers, digitiform on anterior chaetigers, short with a pointed tip on posterior chaetigers ( Fig. 2 A–D). Neuropodia with digitiform inferior and superior lobes on anterior chaetigers, both lobes less developed on posterior chaetigers ( Fig. 2 A–D). Postchaetal lobe present, digitiform on anterior chaetigers, less developed on posterior chaetigers ( Fig. 2 A–D). Neuropodial ventral ligule digitiform with distal tapering throughout; ventral cirri attached to middle of neuropodial ventral surface, shorter than ventral ligule ( Fig. 2 A–D).

Notochaetae present from chaetiger 3 to posterior chaetigers, homogomph spinigers with serrated terminal blade ( Fig. 3A ). Neurochaetae present from chaetiger 1 to posterior chaetigers, neurochaetae of dorsal fascicle arising from base of superior lobe and completely encircled superior lobe, homogomph spinigers and sesquigomph spinigers present, terminal blade with serrations ( Fig. 3B, C ). Neurochaetae of ventral fascicle arising from base of inferior lobe and completely encircled inferior lobe, homogomph and sesquigomph spinigers present on anterior chaetigers ( Fig. 3D, E ), homogomph and sesquigomph spinigers and long blunt-tipped sesquigomph falcigers present on posterior chaetigers, terminal blade with serrations ( Fig. 3 F–H). Pygidium not observed.

Etymology. The name is derived from the name of nearby township, Budai where the worm was collected.

Type locality. Budai , Chiayi County, Taiwan .

Distribution. Only known from the type locality.

Remarks. Of the two species accepted for the genus by Bakken & Wilson (2005), only C. irritabilis (Webster, 1879) has more than 12 paragnaths on Area III of the pharynx as in C. budaiensis n. sp. ( Bakken & Wilson 2005: 521). However, C. budaiensis n. sp. differs from C. irritabilis by having 2–5 conical paragnaths on Area I of the pharynx (versus 0) and the presence of sesquigomph spinigers and sesquigomph falcigers in ventral fascicle of neuropodia on posterior chaetigers (versus only homogomph falcigers) ( Bakken & Wilson 2005: 521; Figs 1B , 3G, H ). Of the remaining 27 species of Ceratonereis (Composetia) listed in Hartmann-Schröder (1985), seven are reported from East and Southeast Asia: C. (C.) burmensis (Monro, 1937) (= Neanthes glandicincta Southern, 1921 ), Ceratonereis (C.) coracina ( Grube, 1878) ( Philippines), C, (C.) costae ( Grube, 1840) (type locality in Mediterranean Sea, reported from China; Wu et al. 1981; Sun & Yang 2004), C. (C.) hircinicola ( Eisig, 1870) (type locality in Mediterranean Sea, reported from China and Japan; Imajima 1972; Wu et al. 1981; Sun & Yang 2004), C. (C.) hyalognatha ( Ehlers, 1920) ( Ambon Island, Indonesia), C. (C.) microcephala ( Grube, 1878) ( Philippines), C. (C.) moorei ( Imajima, 1972) ( Japan) (Salazar et al. 2014; Glasby et al. 2016; Read & Fauchald 2018b). Of these seven species, only C, (C.) costae ( Grube, 1840) and C. (C.) hircinicola ( Eisig, 1870) are somewhat similar to C. budaiensis n. sp. in terms of number of paragnaths on Area II of the pharynx (7–9 versus 7–10) ( Eisig 1870; Grube 1878; Ehlers 1920; Imajima 1972; Wu et al. 1981; Sun & Yang 2004). Composetia budaiensis n. sp., however, can be distinguished from the former two species by having a different paragnath pattern on Areas I, III & IV of the pharynx (2–5, 17–27 & 6–12 versus 0, 8–9, 10–12 and 0–1, 7–10 & 10–24, respectively) ( Eisig 1870; Imajima 1972; Wu et al. 1981; Sun & Yang 2004).

Figures

FIGURE 1. Composetia budaiensis n. sp., holotype (NMNS 7898-001). A, anterior body of the animal, dorsal view; B, closeup of anterior body, dorsal view; C, close-up of anterior body, ventral view. Roman numeric numbers: Areas of the pharynx. Scale: A, 1.0 mm; B, C, 0.5 mm.

FIGURE 2. Composetia budaiensis n. sp.; A, B, paratype (NMNS 7898-002); C, D, paratype (NMNS 7898-004). A, left chaetiger 5, anterior view; B, left chaetiger 5, posterior view; C, left chaetiger 76, anterior view; D, left chaetiger 76, posterior view. Abbreviations: DC, dorsal cirrus; IL, inferior lobe; NePL, neuropodial postchaetal lobe; NeVL, neuropodial ventral ligule; NoDL, notopodial dorsal ligule; NoPL, notopodial prechaetal lobe; NoVL, notopodial ventral ligule; SL, superior lobe; VC, ventral cirrus. Scale: A–D, 0.5 mm.

FIGURE 3. Composetia budaiensis n. sp.; A–C, F–H, paratype (NMNS 7898-004); D, E, paratype (NMNS 7898-002). A, notochaetae, homogomph spinigers, chaetiger 72; B, neuropodial homogomph spinigers, dorsal fascicle, chaetiger 76; C, neuropodial sesquigomph spinigers, dorsal fascicle, chaetiger 76; D, neuropodial homogomph spinigers, ventral fascicle, chaetiger 5; E, neuropodial sesquigomph falciger, ventral fascicle, chaetiger 5; F, neuropodial homogomph spinigers, ventral fascicle, chaetiger 72; G, neuropodial sesquigomph falciger, ventral fascicle, chaetiger 72; H, neuropodial sesquigomph falciger, ventral fascicle, chaetiger 76. Scale: A–H, 0.01 mm.