taxonID	type	description	language	source
9F6887892C6D9C1EFF462FCDFE59AAE7.taxon	diagnosis	Diagnosis (after Glasby & Salazar-Vallejo 2022). Pilargids with body depressed, integument papillose to verrucose, present on both segmental and nonsegmental regions. Zero to three antennae. Palps unfused, biarticulated, palpostyle minute. Paired ventrolateral palpal papillae present. Pharynx distally with terminal papillae (or absent); proximally smooth or, rarely, with denticles. Two pairs of tentacular cirri. Dorsal and ventral cirri digitate to lobate. Notochaetae are hooks, starting from chaetigers 3 to 13 and continuing throughout body. Neurochaetae smooth, or spinulose capillaries, often with bidentate tips. Free living in sediments from intertidal to deep sea, or commensal with other invertebrates.	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
9F6887892C6D9C12FF462D39FCB8A99F.taxon	description	Figs 2 – 5	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
9F6887892C6D9C12FF462D39FCB8A99F.taxon	materials_examined	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.), S 09 - 19 (7 ° 31 ’ 37 ” N, 100 ° 42 ’ 48 ” E), 17 Feb. 2015, 24 m. Paratypes: PSUZC-POL- 0306 (1 spec., on SEM stub), S 06 (7 ° 20 ’ 10 ” N, 100 ° 36 ’ 59 ” E), 12 Feb. 2015, 15.5 m; PSUZC-POL- 0307 (3 specs., 1 spec. on SEM stub), S 08 (7 ° 29 ’ 10 ” N, 100 ° 47 ’ 06 ” E), 16 Mar. 2016, 25 m; PSUZC-POL- 0308 (1 spec., juvenile), S 09 - 11 (7 ° 31 ’ 52 ” N, 100 ° 42 ’ 42 ” E), 25 Mar. 2017, 23 m. Type locality. Songkhla Sea, Gulf of Thailand (Fig. 1).	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
9F6887892C6D9C12FF462D39FCB8A99F.taxon	diagnosis	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.	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
9F6887892C6D9C12FF462D39FCB8A99F.taxon	description	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. 2 A – D). 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 3 A – C, 5 A). Pharynx not observed, retracted in holotype and paratypes, extending to chaetiger 6 (Fig. 2 B). Peristomium fused to prostomium. Two pairs of short, conical, papillose tentacular cirri inserted laterally (Figs 2 B, 3 A – C, 5 A). Dorsal cirri short, first dorsal cirri from chaetiger 1, slightly shorter than dorsal cirri of chaetiger 2 and following chaetigers (Figs 2 B, 3 A – B, 5 A). Parapodia subbiramous. Notopodia reduced to a low swollen lobe, each with single aciculae, 1 – 2 notopodial hooks per parapodium from chaetiger 3 (Figs 2 B, 3 A – B, 4 B – E, 5 A – B). Neuropodia well developed with conical lobes. Ventral cirri from chaetiger 1, shorter than dorsal cirri and slightly longer than neuropodial lobes (Figs 3 A – B, 4 B, C, E, 5 A – B). 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 4 C, F – G, 5 B, C). 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. 2 D, F). Habitat. Found in 15.5 – 25 m water depth, in mud substrates, mixed with sand and shells.	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
9F6887892C6D9C12FF462D39FCB8A99F.taxon	distribution	Distribution. Songkhla Sea, the Gulf of Thailand, Western Pacific.	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
9F6887892C6D9C12FF462D39FCB8A99F.taxon	etymology	Etymology. The new species is name after Mrs Elena Eidimtaite, grandmother of Dr Ted Donn, Principal Ecologist at Tetra Tech, Inc.	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
9F6887892C6D9C12FF462D39FCB8A99F.taxon	discussion	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). 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).	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
9F6887892C629C15FF462EEDFB2EA99F.taxon	description	Figs 6 – 9	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
9F6887892C629C15FF462EEDFB2EA99F.taxon	materials_examined	Material examined. Nine specimens collected from the Songkhla Sea and offshore in the Gulf of Thailand, coll. Marine Ecosearch Management Co., Ltd., mud mixed with sand and shells. Holotype: PSUZC-POL- 0345 (1 spec.), S 02 (7 ° 31 ’ 44 ” N, 100 ° 28 ’ 15 ” E), 21 Sep. 2016, 10 m. Paratypes: S 01 (7 ° 46 ’ 29 ” N, 100 ° 24 ’ 42 ” E), 16 Oct. 2013, 9.5 m; PSUZC-POL- 0346 (3 specs., 1 spec. on SEM stub), S 01 - B 1; PSUZC-POL- 0347 (1 spec.), S 01 - B 3; PSUZC-POL- 0348 (1 spec., on SEM stub), S 03 (7 ° 21 ’ 02 ” N, 100 ° 31 ’ 45 ” E), 13 Oct. 2015, 9 m; PSUZC-POL- 0349 (1 spec.), GT-UR (8 ° 20 ’ 16 ” N, 101 ° 45 ’ 01 ” E), 9 Sep. 2015, 70 m; PSUZC-POL- 0350 (2 specs., 1 spec. on SEM stub), GT-SW (9 ° 22 ’ 59 ” N, 101 ° 21 ’ 37 ” E), 22 May 2020, 50 m. Type locality. Songkhla Sea, Gulf of Thailand (Fig. 1).	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
9F6887892C629C15FF462EEDFB2EA99F.taxon	diagnosis	Diagnosis. Ancistrosyllis without eyespots; with a short median antenna and two short lateral antennae. With a pair of short tentacular cirri; dorsal and ventral cirri starting from chaetiger 1. Notopodial hooks from chaetiger 4. Three types of neurochaetae; short, stout, falcates with a small subdistal guard; short limbates with bifid tips; and long non-limbate capillaries with bifid tips.	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
9F6887892C629C15FF462EEDFB2EA99F.taxon	description	Description. Holotype complete (pygidial cirri broken), 22.3 mm long, 0.7 mm wide, 99 segments. Paratypes incomplete, anterior region 1.8 – 8.2 mm long, 0.3 – 0.8 mm wide with 10 – 36 segments. Two posterior parts with pygidial cirri. Body depressed, light tan to light brown with numerous light yellow to brown papillae, widest in middle region, tapering anteriorly and posteriorly (Fig. 6 A – C). Prostomium short, broad, bilobed, wider than long, with numerous brown papillae; short, small median antenna present on posterior prostomial region; two short lateral antennae present antero-laterally on prostomium, shorter than palps and tentacular cirri (Figs 6 B, 7 – D, 9 A). Eyespots absent. Palps biarticulate with very small ventrolateral palpal papillae (Figs 7 B, 7 D, 9 B). Pharynx not observed, retracted in holotype and paratypes, extending to chaetiger 4 (Fig. 6 B). Peristomium with two pairs of short, digitate, papillate tentacular cirri, longer than lateral antennae, inserted laterally. Dorsal cirri present from chaetiger 1, long, conical, papillose, twice as long as dorsal cirri of chaetiger 2. Ventral cirri present from chaetiger 1, shorter than dorsal cirri (Figs 6 B, 7 A – D, 9 A – B). Parapodia subbiramous, notopodia reduced with a single acicula. Notopodial hooks present from chaetiger 4; large, strong falcate, 1 – 2 hooks per parapodium with the second one non-emergent (Figs 6 B, 6 C, 7 A – B). Neuropodia well-developed conical lobes, conical with a single aciculum (Figs 6 A – B, 7 A – B, 8 A, 9 B). Neurochaetae three types: two types of short chaetae and one type of long non-limbate chaeta; 1) short, stout falcates, with small subdistal guard approaching distal tips (Figs 8 A-C, 9 C), 2) short limbate with bifid tips (Figs 8 A, B, D, 9 C) and 3) long non-limbate capillaries with bifid tips (Fig. 8 A, E). Each neuropodium with 5 – 7 long nonlimbate capillaries above neuroacicula and 1 – 2 short, stout falcates with a subdistal guard, 2 – 3 short bifid limbates, and 1 long non-limbate below neuroacicula (Figs 8 A – E, 9 C). Pygidium conical with pair of anal cirri. Small oocytes were found in the body and parapodia of large specimen collected in October 2013 (Fig. 6 D).	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
9F6887892C629C15FF462EEDFB2EA99F.taxon	etymology	Etymology. The new species is named in honor of Mr. Suksan Jinanarong, the senior staff of Tetra Tech, Inc. (Thailand) for his work on marine benthos of Songkhla Sea, Gulf of Thailand with our team (MEM and Coral Reefs and Benthos Research Unit) from the beginning of our research. Habitat. Living in 9 – 70 m water depth, mud mixed with sand and shells.	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
9F6887892C629C15FF462EEDFB2EA99F.taxon	distribution	Distribution. Gulf of Thailand, Western Pacific (Fig. 1).	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
9F6887892C629C15FF462EEDFB2EA99F.taxon	discussion	Remarks. Ancistrosyllis suksani sp. nov. belongs to the group II of Ancistrosyllis characterized by the presence of both a median antenna and two lateral antennae. It resembles A. groenlandica McIntosh, 1878 in having the first dorsal and ventral cirri from chaetiger 1 and the first notopodial hooks from chaetiger 4 (Table 1). However, A. suksani sp. nov. differs from A. groenlandica regarding neurochaetae in that it has three different types: 1) short, stout falcates with a subdistal guard approaching distal tips, 2) short bifid limbates, and 3) long non-limbate capillaries with bifid tips. Ancistrosyllis groenlandica has only two types of neurochaetae: short limbates and long non-limbate capillaries with slightly hooked tips (Imajima 1987; Pettibone 1966). Moreover, the first notopodial hooks of A. suksani sp. nov. always starts from chaetiger 4, whereas in A. groenlandica the first notopodial hooks occurs variably from chaetiger 4 to 6 (Imajima 1987; Pettibone 1966). Ansistrosyllis suksani sp. nov. is clearly distinguished from other species of group II of Ancistrosylis species by having the first notopodial hooks at chaetiger 4, and having three types of neurochaetae (Table 1).	en	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): 195-210, DOI: 10.11646/zootaxa.5128.2.2
