Ancistrosyllis eidimtaiteae, Plathong & Plathong & Dean, 2022

Plathong, Sakanan, Plathong, Jintana & Dean, Harlan K., 2022, Two new species of Ancistrosyllis McIntosh, 1878 (Annelida: Pilargidae) from the Gulf of Thailand, Western Pacific, Zootaxa 5128 (2), pp. 195-210 : 200-204

publication ID	https://doi.org/ 10.11646/zootaxa.5128.2.2
publication LSID	lsid:zoobank.org:pub:01AAFD2B-BA1B-409B-B027-BA546B313BD8
DOI	https://doi.org/10.5281/zenodo.6499045
persistent identifier	https://treatment.plazi.org/id/9F688789-2C6D-9C12-FF46-2D39FCB8A99F
treatment provided by	Plazi
scientific name	Ancistrosyllis eidimtaiteae
status	sp. nov.

Treatment

Ancistrosyllis eidimtaiteae View in CoL sp. nov.

Figs 2–5 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5

Material examined. Six specimens collected from the Songkhla Sea , Gulf of Thailand, Western Pacific, coll. Marine Ecosearch Management Co., Ltd., mud mixed with sand and shells. Holotype: PSUZC-POL-0305 (1 spec.), S09-19 (7°31’37”N, 100°42’48”E), 17 Feb. 2015, 24 m. GoogleMaps Paratypes: PSUZC-POL-0306 (1 spec., on SEM stub), S06 (7°20’10”N, 100°36’59”E), 12 Feb. 2015, 15.5 m; PSUZC-POL-0307 (3 specs., 1 spec. on SEM stub), S08 (7°29’10”N, 100°47’06”E), 16 Mar. 2016, 25 m; PSUZC-POL-0308 (1 spec., juvenile), S09-11 (7°31’52”N, 100°42’42”E), 25 Mar. 2017, 23 m.

Type locality. Songkhla Sea, Gulf of Thailand ( Fig. 1 View FIGURE 1 ).

Diagnosis. Ancistrosyllis with body papillae brown, lacking eyespots, with small median antenna, and two short papillose lateral antennae. Tentacular cirri short, first dorsal and ventral cirri from chaetiger 1. First notopodial hooks from chaetiger 3.

Description. Holotype incomplete, 6.3 mm long, 0.5 mm wide with 33 segments. Paratypes, 2.0– 22.2 mm long, 0.3–0.6 mm wide, 18–125 chaetigers. Longest specimen consists of three pieces: anterior region, 7.1 mm long with 41 chaetigers; middle region, 11.5 mm long with 55 chaetigers and posterior region with broken anal cirri, 3.6 mm long with about 29 chaetigers. Body annulated, depressed anteriorly, depressed, tapered posteriorly. Body light tan in ethanol with brownish papillae throughout. Ventral with a deep midventral groove running longitudinally ( Fig. 2A–D View FIGURE 2 ).

Prostomium broad, bilobed, wider than long with a small median antenna present in prostomial posterior region. Lateral antennae short papillose, shorter than palps. Eyespots absent. Palps biarticulate with very small ventrolateral papillae, visible ventrally ( Figs 3A–C View FIGURE 3 , 5A View FIGURE 5 ). Pharynx not observed, retracted in holotype and paratypes, extending to chaetiger 6 ( Fig. 2B View FIGURE 2 ).

Peristomium fused to prostomium. Two pairs of short, conical, papillose tentacular cirri inserted laterally ( Figs 2B View FIGURE 2 , 3A–C View FIGURE 3 , 5A View FIGURE 5 ). Dorsal cirri short, first dorsal cirri from chaetiger 1, slightly shorter than dorsal cirri of chaetiger 2 and following chaetigers ( Figs 2B View FIGURE 2 , 3A–B View FIGURE 3 , 5A View FIGURE 5 ).

Parapodia subbiramous. Notopodia reduced to a low swollen lobe, each with single aciculae, 1–2 notopodial hooks per parapodium from chaetiger 3 ( Figs 2B View FIGURE 2 , 3A–B View FIGURE 3 , 4B–E View FIGURE 4 , 5A–B View FIGURE 5 ).

Neuropodia well developed with conical lobes. Ventral cirri from chaetiger 1, shorter than dorsal cirri and slightly longer than neuropodial lobes ( Figs 3A–B View FIGURE 3 , 4B, C, E View FIGURE 4 , 5A–B View FIGURE 5 ). Neurochaetae non-limbate capillary chaetae with bifid tips, variable in length, throughout the body. Inferior chaetae are shorter than superiorr chaetae, up to 9 chaetae per bundle ( Figs 4C, F–G View FIGURE 4 , 5B, C View FIGURE 5 ).

Pygidium with two anal cirri.

Holotype and paratypes of A. eidimtaiteae sp. nov. collected in March had oocytes in the coelomic cavities of posterior chaetigers. Diameter of larger oocytes 60–72 μm ( Fig. 2D, F View FIGURE 2 ).

Habitat. Found in 15.5–25 m water depth, in mud substrates, mixed with sand and shells.

Distribution. Songkhla Sea, the Gulf of Thailand, Western Pacific.

Etymology. The new species is name after Mrs Elena Eidimtaite, grandmother of Dr Ted Donn, Principal Ecologist at Tetra Tech, Inc.

Remarks. Ancistrosyllis eidimtaiteae sp. nov. belongs to Group II of Ancistrosyllis because it has a median and two lateral antennae. Moreover, A. eidimtaiteae sp. nov. has first notopodial hooks from chaetiger 3 and distinctive brownish body papillae. These features make it easy to differentiate from other colorless species. The new species resembles four other species of subgroup A: A. hartmanae Pettibone, 1966 ; A. fioronii Fiege & Böggemann, 1999 ; A. kornkanokae Plathong, Dean & Plathong, 2021 and A. nakkaritae Plathong, Dean & Plathong, 2021 ( Table 1 View TABLE 1 ).

Ancistrosyllis eidimtaiteae sp. nov. differs from A. hartmanae Pettibone, 1966 in lacking eyespots and the first ventral cirri appearing at chaetiger 1, whereas A. hartmanae has a pair of eyespots and the first ventral cirri from chaetiger 3 ( Pettibone 1966).

Ancistrosyllis eidimtaiteae sp. nov. differs from A. fioronii by the first ventral cirri present from chaetiger 1, having well developed, conical, truncate neuropodia, and non-limbate capillaries with bifid tips. Ancistrosyllis . fioronii has the first ventral cirri occurring from chaetiger 2, the neuropodia are poorly developed and the tips of long non-limbate capillary chaetae are bidentate ( Fiege & Böggemann 1999). Moreover, the number of neurochaetae per fascicle in A. eidimtaiteae sp. nov. is greater than in A. fioronii with up to 6–9 chaetae per fascicle, rather than 4–6 chaetae per fascicle. Additionally, the body color of A. eidimtaiteae sp. nov. is brown but A. fioronii lacks pigmentation ( Fiege & Böggemann 1999).

Ancistrosyllis eidimtaiteae sp. nov. differs from A. kornkanokae Plathong, Dean & Plathong, 2021 in the neurochaetae and the first appearance of ventral cirri. Ancistrosyllis eidimtaiteae sp. nov. has a single type of non-limbate capillary chaetae with bifid tip, and the first ventral cirri appearing at chaetiger 1, whereas A. kornkanokae bears two types of unidentate neurochaetae, short limbate and long, non-limbate capillaries and the first ventral cirri occur from chaetiger 3. In addition, tentacular cirri and the first dorsal cirri in A. eidimtaiteae sp. nov. are shorter than in A. kornkanokae , and the body is brown in color in alcohol, whereas A. kornkanokae is lacking colour ( Plathong et al. 2021).

Ancistrosyllis eidimtaiteae sp. nov. most closely resembles A. nakkaritae Plathong, Dean & Plathong, 2021 in having the first ventral cirri at chaetiger 1 and the first notopodial hooks from chaetiger 3. However, A. eidimtaiteae sp. nov. differs from A. nakkaritae by having only non-limbate capillaries, and lacks short limbate capillaries. Ancistrosllis nakkaritae has both short limbates and long non-limbate capillaries. Moreover, the lateral antennae, tentacular cirri and dorsal cirri of A. eidimtaiteae sp. nov. are shorter than those of A. nakkaritae ( Plathong et al. 2021) .

Finally, Ancistrosyllis eidimtaiteae sp. nov. differs from A. suksani sp. nov. in having a single type of neurochaetae and first notopodial hooks occurring at chaetiger 3 while A. suksani sp. nov. has three types of neurochaetae and the first notopodial hooks appear at chaetiger 4 ( Table 1 View TABLE 1 ).