Three New Polychaete Species of Platynereis (Annelida, Polychaeta, Nereididae) from Taiwan

© 2022 Academia Sinica, Taiwan Open Access Three New Polychaete Species of Platynereis (Annelida, Polychaeta, Nereididae) from Taiwan Pan-Wen Hsueh1,* 1Department of Life Sciences, National Chung Hsing University, 145 Xingda Rd., Taichung City 402, Taiwan. *Correspondence: E-mail: [email protected] (Hsueh) Received 11 August 2021 / Accepted 17 April 2022 / Published 21 July 2022 Communicated by Benny K.K. Chan The present study describes three new species of Platynereis Kinberg, 1865 from Taiwan to provide a better understanding of the diversity of Platynereis in the tropical Western Pacific. Platynereis hemeiensis sp. nov. is similar to P. abnormis (Horst, 1924), P. australis (Schmarda, 1861), P. hutchingsae de LeonGonzalez, Solis-Weiss and Valadez Rocha, 2001, and P. sinica Sun, Shen and Wu, 1978 in terms of having no notopodial homogomph falcigers in adults. However, P. hemeiensis sp. nov. differs from P. australis by having: 1) fewer transverse rows or diagonal lines in Areas III, IV, VI and VII–VIII (2–3, 6–8, 2 and 2 versus 5, 10, 4 and 4, respectively); 2) tapered dorsal cirri on anterior-most chaetigers (versus stout dorsal cirri); and 3) dorsal cirri always shorter than dorsal ligule in posterior chaetigers (versus always longer than dorsal ligule). Platynereis hemeiensis sp. nov. can be distinguished from P. abnormis and P. sinica by having transverse rows of pectinate paragnaths in Area III (versus no pectinate paragnaths). Platynereis hemeiensis sp. nov. can be readily differentiated from P. hutchingsae by having long-bladed heterogomph spinigers in neuropodia (versus short-bladed heterogomph spinigers). Both P. jihueiensis sp. nov. and P. shihmenensis sp. nov. are somewhat similar to P. bicanaliculata (Baird, 1863), because all have bifid tip of notopodial anchylosed falcigers. However, the two species differ from P. bicanaliculata by having either no pectinate paragnaths or rows of pectinate paragnaths in Area III (versus a broad, oval patch of pectinate paragnaths). Platynereis jihueiensis sp. nov. differs from P. shihmenensis sp. nov. by having: 1) three groups of pectinate paragnaths in Area III (versus no pectinate paragnaths); 2) six to seven transverse rows of pectinate paragnaths in Area IV (versus four transverse rows); 3) three parallel transverse rows of pectinate paragnaths in Area VI (versus three to four non-parallel rows); 4) seven groups of transverse rows of pectinate paragnaths in Areas VII–VIII, middle groups each with three rows and two outer most groups each with one and two paragnaths (versus five groups of transverse rows of pectinate paragnaths, middle groups each with 1–2 rows and two outer most groups each with one paragnath); and 5) each parapodium of chaetigers in anterior, mid-body and posterior regions with three, two and one notopodial homogomph falcigers, respectively (versus each parapodium with one notopodial homogomph falciger in all body regions). A key for identifying Platynereis species from East Asia is provided. Key words: Nereidinae, Platynereis, Polychaetes, Taxonomy, Taiwan. BACKGROUND Polychaeta Grube, 1850 is the largest and most diverse group in the Phylum Annelida, which has been classified to 25 orders, 87 families, with over 10,000 species described (Brusca and Brusca 1990). Of these families, the family Nereididae Blainville, 1818 is one of the most diverse polychaete families with 43 valid genera and about 770 valid species, many of which are most common and species rich in shallow marine Citation: Hsueh P-W. 2022. Three new species of Platynereis (Annelida, Polychaeta, Nereididae) from Taiwan. Zool Stud 61:30. doi:10.6620/ ZS.2022.61-30. Zoological Studies 61:30 (2022) doi:10.6620/ZS.2022.61-30 1 © 2022 Academia Sinica, Taiwan habitats (Bakken et al. in press). The genus Platynereis Kinberg, 1865 is characterized by having parallel rows of pectinate paragnaths on both maxillary and oral rings of the pharynx (Bakken and Wilson 2005; Read 2007). Thirtytwo valid species are known to the genus worldwide (Read and Fauchald 2021). Of these species, only six were reported from East Asia, and they are: P. abnormis (Horst, 1924) (type locality: Indonesia), P. bicanaliculata (Baird, 1863) (type locality, Canada), P. australis (Schmarda, 1861) (type locality, New Zealand), P. dumerilii (Audouin et Milne-Edwards, 1834) (type locality, France), P. pulchella Gravier, 1901 (type locality, Djibouti), and P. sinica Sun, Wu and Shen, 1978 (type locality, China) (Imajima 1972; Sun and Yang 2004). In Taiwan, two Platynereis species were reported: P. bicanaliculata and P. dumerilii (Wu 1967; Imajima 1972; Wu et al. 1981; Sun and Yang 2004). However, with many new species of nereidids recently described for other genera in the family from Taiwan (Hsueh 2019a b 2020 2021), the diversity of Platynereis in this geographic region has been overlooked. In the present study, the author examines three unidentified Platynereis species collected from ecological surveys in coasts of Taiwan. The results indicate the three species have unique morphological characters that are not seen in other congeners reported from East Asia. Three new species are herein described, and a key for the species of Platynereis in East Asia is also provided. MATERIALS AND METHODS Specimens in the present study were collected from various ecological surveys in coasts of Taiwan. They were fixed with 10% buffered formalin and later transferred into 70% alcohol for storage. In the laboratory, worms were examined using stereo (Leica MZ12.5) and compound microscopes (Leica DM2500). Images of the worms and their body parts were taken using digital camera. Some images were stacked using computer software (Helicon Focus 7.0.2) to improve their depth of field. Terminology of prostomium region and chaetal morphology followed Bakken and Wilson (2005); description of parapodia followed VillalobosGuerrero and Bakken (2018); and description of pattern of areas VI–V–VI followed Villalobos-Guerrero (2019). Length measurements of dorsal ligule and dorsal cirrus followed Conde-Vela (2018: 257, fig. 6C–F). All specimens of this study were deposited into the National Museum of Natural Science (NMNS), Republic of China. Numbers in parentheses represent the variations in a given morphological character. TAXONOMY Family Nereididae Blainville, 1818 Subfamily Nereidinae Blainville, 1818 Genus Platynereis Kinberg, 1865 Platynereis hemeiensis sp. nov. (Figs. 1A–C, 2A–F, 3A–E) urn:lsid:zoobank.org:act:05DBCFA0-D0A7-4797-B4858BF223C3729B Material examined: Holotype, NMNS8390-1, Hemei (25°2.6'N 121°55.8'E), Gongliao District, New Taipei City, Taiwan, intertidal rocky habitats, coll. S.-M. Chao, 12 Mar. 1989. Paratype: 1 specimen, NMNS83902, Longdong (25°5.1'N 121°55.2'E), Gongliao District, New Taipei City, Taiwan, intertidal rocky habitats, coll. H.-T. Hong, 3 Jun. 1996. Etymology: The name is derived from the name of the nearby village, Hemei, in northeastern Taiwan where the holotype was collected. Diagnosis: Platynereis with longest tentacular cirri reaching chaetiger 4. Dark brown jaws, each with 4 lateral teeth; paragnath pattern: I = 0; II = 0; III = 5 groups of pectinate paragnaths, each group with 2–3 parallel transverse rows; IV = 6–8 parallel diagonal lines of pectinate paragnaths, innermost 2–3 lines incomplete in the middle; V = 0; VI = 2 parallel transverse rows of pectinate paragnaths on each side; VII–VIII = 5 groups of pectinate paragnaths, each group with 2 parallel transverse rows. Notopodial prechaetal lobe present on anterior to mid-body chaetigers. Neuropodial postchaetal lobe present throughout. Notochaetae with homogomph spinigers throughout, without homogomph falcigers. Neurochaetae with homogomph spinigers throughout; dorsal fascicle with heterogomph spinigers on chaetigers 1–4, short-bladed heterogomph falcigers with recurved tip and serrations present throughout except chaetigers 1–4; ventral fascicle with heterogomph spinigers on chaetigers 1–4 and mid-body to posterior chaetigers, short-bladed heterogomph falcigers with recurved tip and serrations present throughout except chaetigers 1–4. Description: Holotype complete, 39.0 mm long, 86 chaetigers, chaetiger 10 width 2.0 mm (2.5, n = 1), excluding parapodia; beige in alcohol (Fig. 1A). Prostomium slightly longer than wide, lateral antennae separated basally, as long as palps; palpophores globose, palpostyles half as long as palpophores, blunt, medially widest, four pairs of tentacular cirri, longest one reaching chaetiger 4. Two pairs of eyes, in trapezoidal arrangement, separated from each other, subequal in size; anterior eyes 1/7–1/8 as wide as prostomium. Tentacular belt about 1.2 times (1.5 times, n = 1) longer page 2 of 13Zoological Studies 61:30 (2022) © 2022 Academia Sinica, Taiwan than chaetiger 1. Pharynx with dark brown jaws, each with 4 lateral teeth; paragnath pattern: I = 0; II = 0; III = 5 groups of pectinate paragnaths, each group with 2–3 parallel transverse rows; IV = 6–7 (7–8, n = 1) parallel diagonal lines of pectinate paragnaths, innermost 2–3 lines incomplete in the middle; V = 0; VI = 2 parallel transverse rows of pectinate paragnaths on each side; VII–VIII = 5 groups of pectinate paragnaths, each group with 2 parallel transverse rows (Fig. 1B–C). Ridge pattern of Areas VI–V–VI, υ-shaped (Fig. 1A–B). Dorsal cirri tapered, basally attached to dorsal ligule throughout, about as long as dorsal ligule on anterior chaetigers, about 0.7–0.8 times as long as dorsal ligule on mid-body to posterior chaetigers (Fig. 2A–F). Notopodial prechaetal lobe present on anterior to mid-body chaetigers (Fig. 2C, D). Dorsal ligule narrow conical on anterior-most chaetigers, conical from chaetiger 5 to 11 (5 to 12, n = 1), narrow conical with blunt tip on second-half portion of anterior to posterior chaetigers (Fig. 2A–F); base of dorsal ligule slightly bulged on anterior chaetigers, elongate and broader on mid-body chaetigers, markedly elongate and broader on posterior chaetigers (Fig. 2A– F); small, beige glandular patches present on anterior chaetigers, glandular patches becoming light yellow, enlarged and fused into large mass on mid-body to posterior chaetigers (Fig. 2A–F). Median ligule subconical on anterior-most chaetigers, about 0.9 as long as dorsal ligule; conical from chaetiger 5 to 11 (5 to 12, n = 1), subconical with blunt tip on posterior portion of anterior to posterior chaetigers, about 0.8 times as long as dorsal ligule (Fig. 2A–F). Neuroacicular ligule subconical acute on anterior chaetigers, subconical blunt tip on mid-body to posterior chaetigers, about 0.4–0.5 times as long as ventral ligule (Fig. 2A–F). Neuropodial postchaetal lobe present throughout, subconical on anterior-most chaetigers, about 1.8 times longer than neuroacicular ligule; conical on chaetiger 5 to 11 (5 to 12, n = 1), about 0.5 times as long as neuroacicular ligule; subconical on mid-body to posterior chaetiger, about as long as neuroacicular ligule (Fig. 2A–F). Ventral ligule narrow conical on anterior-most chaetigers, conical on chaetiger 5 to 11 (5 to 12, n = 1), narrow conical on mid-body to posterior chaetigers (Fig. Fig. 1. Platynereis hemeiensis sp. nov.; holotype (NMNS 8390-1): A, anterior region, dorsal view; B, dorsal view of the pharynx; C, frontal view of the pharynx. Roman numerals indicate Area number of the pharynx. Scale bars: A = 1.0 mm; B–C = 0.5 mm. page 3 of 13Zoological Studies 61:30 (2022) © 2022 Academia Sinica, Taiwan 2A–F). Ventral cirri basally attached to ventral edge of parapodia, about as long as ventral ligule on anteriormost chaetigers, about 1.5 times longer than ventral ligule on chaetiger 5 to 11 (5 to 12, n = 1), about 0.8 times as long as ventral ligule on mid-body to posterior chaetigers (Fig. 2A–F). Notochaetae present from chaetiger 3 to posterior chaetigers, homogomph spinigers present throughout, homogomph falcigers absent. Neurochaetae dorsal fascicle: homogomph spinigers present throughout, heterogomph spinigers present on chaetigers 1–4, shortbladed heterogomph falcigers with recurved tip and serrations present throughout except chaetigers 1–4. Neurochaetae ventral fascicle: heterogomph spinigers present on chaetigers 1–4 and mid-body to posterior chaetigers, short-bladed heterogomph falcigers with recurved tip and serrations present throughout except chaetigers 1–4 (Fig. 3A–E). Type locality: Hemei, New Taipei City, Taiwan. Distribution: Only known from the type locality and Longdong, New Taipei City, Taiwan. Remarks: Platynereis hemeiensis sp. nov. is similar to P. abnormis (Horst, 1924), P. australis (Schmarda, 1861), P. hutchingsae de Leon-Gonzalez, Solis-Weiss & Valadez Rocha, 2001, and P. sinica Sun, Wu and Shen, 1978 in term of lacking notopodial homogomph falcigers in adults (Horst 1924: 164; Read 2007: 6; de Leon Gonzalez et al. 2001: 390–391; Sun and Young 2004: 220; Fig. 3). Of the latter four species, only P. australis has paragnath patterns somewhat similar to that of P. hemeiensis sp. nov. However, P. hemeiensis sp. nov. differs from P. australis by having fewer transverse Fig. 2. Platynereis hemeiensis sp. nov.; holotype (NMNS 8390-1): A, left parapodium, anterior view, chaetiger 4; B, left parapodium, posterior view, chaetiger 4; C, left parapodium, anterior view, chaetiger 10; D, left parapodium, anterior view, chaetiger 29; E, left parapodium, anterior view, chaetiger 50; F, left parapodium, anterior view, chaetiger 70. Abbreviations: DC, dorsal cirrus; NeAL, neuropodial acicular lobe; NePL, neuropodial postchaetal lobe; NeVL, neuropodial ventral ligule; NoDL, notopodial dorsal ligule; NoPL, notopodial prechaetal lobe; NoVL, notopodial ventral ligule; VC, ventral cirrus. Scale bars: A–F = 0.1 mm. page 4 of 13Zoological Studies 61:30 (2022) © 2022 Academia Sinica, Taiwan rows or diagonal lines in Areas III, IV, VI and VII–VIII (2–3, 6–8, 2 and 2 versus 5, 10, 4 and 4, respectively), in addition to the shape of dorsal cirri on anterior-most chaetigers and the length of dorsal cirri to dorsal ligule in posterior chaetigers (see the Key) (Read 2007: 6–7, fig. 1A–D, F; Fig. 1A–C, F). Platynereis hemeiensis sp. nov. can be distinguished from P. abnormis and P. sinica by having parallel transverse rows of pectinate paragnaths in Area III (versus no pectinate paragnaths) (Horst 1924: 20; Wu et al. 1981; Sun and Young 2004: 210; Fig. 1B–C). Platynereis hemeiensis sp. nov. can be readily differentiated from P. hutchingsae by having long-bladed heterogomph spinigers (versus short-bladed heterogomph spinigers) and short-bladed heterogomph falcigers with recurved tip and serrations (versus shortbladed heterogomph falcigers without recurved tip) in dorsal fascicle of neuropodia (de Leon Gonzalez et al. 2001: 390–391, fig. 1e, g; Fig. 3C). Platynereis jihueiensis sp. nov. (Figs. 4A–F, 5A–F, 6A–F) urn:lsid:zoobank.org:act:AE4C0ACA-A334-4674-95BA18AEB2CD8D4F Material examined: Holotype (NMNS 83903), Jihuei (23°6.97'N 121°24.31'E), Taitung County, Taiwan, intertidal rocky habitats, coll. Li, Y.-H., 7 October 2010. Etymology: The name is derived from the name of the nearby village, Jihuei, where the worm was collected. Diagnosis: Platynereis with longest tentacular cirri reaching chaetiger 7. Light brown jaws, each with 5–6 lateral teeth; paragnath pattern: I = 0; II = 0; III = 3 groups of pectinate paragnaths, each group with 1 or 2 parallel transverse rows; IV = 6 parallel transverse rows and one oblique row of pectinate paragnaths (left), 7 parallel transverse rows and one oblique row of pectinate paragnaths (right); V = 0; VI = 3 parallel transverse rows of pectinate paragnaths on each side; VII–VIII = 7 groups of transverse rows, middle groups each with 3 parallel rows of pectinate paragnaths and 2 outer most groups each with 1 or 2 paragnaths. Notopodial prechaetal lobe present from about chaetiger 15 to posterior end. Neuropodial postchaetal lobe present throughout. Notochaetae with homogomph spinigers throughout, anchylosed falcigers present from chaetiger 12 to posterior end with three anchylosed falcigers on anterior chaetigers, two on midbody chaetigers and one along posterior chaetigers. Neurochaetae with homogomph spinigers throughout; dorsal fascicle with heterogomph spinigers on chaetigers 1–4, short-bladed heterogomph falcigers with recurved tip and serrations present throughout except chaetigers Fig. 3. Platynereis hemeiensis sp. nov.; A–C, E, paratype (NMNS 8390-2); D, holotype (NMNS 8390-1): A, notochaeta, homogomph spiniger, chaetiger 38; B, neurochaeta of dorsal fascicle, homogomph spiniger, chaetiger 38; C, neurochaeta of dorsal fascicle, short-bladed heterogomph falciger, chaetiger 38; D, neurochaeta of ventral fascicle, heterogomph spiniger, chaetiger 70; E, neurochaeta of ventral fascicle, short-bladed heterogomph falciger, chaetiger 38. Scale bars: A–E = 0.01 mm. page 5 of 13Zoological Studies 61:30 (2022) © 2022 Academia Sinica, Taiwan 1–4; ventral fascicle with heterogomph spinigers on chaetigers 1–4 and mid-body to posterior chaetigers, short-bladed heterogomph falcigers with recurved tip and serrations present throughout except chaetigers 1–4. Description: Holotype complete, 39.0 mm long, 79 chaetigers mm, chaetiger 10 width 1.5 mm, excluding parapodia; beige in alcohol (Fig. 4A, B). Prostomium as long as wide, lateral antennae as long Fig. 4. Platynereis jihueiensis sp. nov.; holotype (NMNS 8390-3): A, whole animal; B, anterior body; C, paragnaths of the maxillary and oral rings; D, close-up of Area III; E, close-up of Area VI; F, close-up of Area VII/VIII. Roman numerals indicate Area of the pharynx. Scale bars: A = 2.0 mm; B = 1.0 mm; C = 0.5 mm; D = 0.1 mm; E–F = 0.2 mm. page 6 of 13Zoological Studies 61:30 (2022) © 2022 Academia Sinica, Taiwan as palps; palpophores globose, palpostyles globose, as long as wide, four pairs of tentacular cirri, longest one reaching chaetiger 7. Two pairs of eyes, in trapezoidal arrangement, subequal in size, almost fused to each other laterally; anterior eyes 1/6 as long as prostomial width. Tentacular belt about as long as chaetiger 1. Pharynx with light brown jaws, with 5–6 lateral teeth; paragnath pattern: I = 0; II = 0; III = 3 groups of pectinate paragnaths, each group with 1 or 2 parallel transverse rows (Fig. 4C–D); IV = 6 parallel transverse rows and one oblique row of pectinate paragnaths (left), 7 parallel transverse rows and one oblique row of pectinate paragnaths (right) (Fig. 4C); V = 0; VI = 3 parallel transverse rows of pectinate paragnaths on each side (Fig. 4C, E); VII–VIII = 7 groups of transverse rows, middle groups each with 3 parallel rows of pectinate paragnaths and 2 outer most groups each with 1 or 2 paragnaths (Fig. 4F). Ridge pattern of Areas VI– V–VI, υ-shaped (Fig. 4E). Dorsal cirri tapered, basally attached to dorsal ligule throughout, about 1.2–1.4 times longer than dorsal ligule on anterior chaetigers, about 1.1 times longer than dorsal ligule on mid-body chaetigers, about 0.9–1.0 times as long as dorsal ligule on posterior chaetigers; dorsal cirrus lamellae present on chaetiger 17 to about chaetiger 70 (Fig. 5A–F). Notopodial prechaetal lobe present from about chaetiger 15 to posterior end (Fig. 5D–F). Dorsal ligule conical on chaetigers 1–10, subconical thereafter (Fig. 5A–F); base of dorsal ligule slightly bulged on anterior chaetigers, elongate and broader on mid-body chaetigers, markedly elongate and Fig. 5. Platynereis jihueiensis sp. nov.; holotype (NMNS 8390-3): A, left parapodium, anterior view, chaetiger 3 (notopodial postchaetal lobe hindered by notopodial ventral ligule); B, left parapodium, posterior view, chaetiger 3; C, left parapodium, anterior view, chaetiger 10; D, left parapodium, anterior view, chaetiger 30; E, left parapodium, anterior view, chaetiger 50; F, left parapodium, anterior view, chaetiger 68. Abbreviations: DCLa, dorsal cirrus lamellae; NePL, neuropodial postchaetal lobe; NePLa, neuropodial postchaetal lamellae; NoPL, notopodial prechaetal lobe; VC, ventral cirrus; VCLo, ventral cirrus lobe. Scale bars: A–F = 0.1 mm. page 7 of 13Zoological Studies 61:30 (2022) © 2022 Academia Sinica, Taiwan broader on posterior chaetigers; small, beige glandular patches present on anterior chaetigers, glandular patches becoming light yellow, enlarged and partially or complete fused into large mass on mid-body to posterior chaetigers (Fig. 5A–F). Median ligules conical on chaetigers 1–10, subconical thereafter (Fig. 5A–F). Neuroacicular ligules subequal throughout. Neuropodial postchaetal lobe present throughout, about 2.0 times than neuroacicular ligules on anterior most chaetigers, about as long as, or shorter than neuroacicular ligules thereafter; neuropodial postchaetal lamellae present on chaetiger 17 to about chaetiger 65 (Fig. 5A– F). Ventral ligule conical on chaetigers 1–10, subconical thereafter. Ventral cirri mid-ventrally attached to ventral edge of parapodia, about as long as ventral ligule on chaetigers 1–10, about 1.2 times longer than ventral cirri thereafter; ventral cirrus lobe present on dorsal surface of ventral cirrus from chaetiger 17 to about chaetiger 65 (Fig. 5A–F). Notochaetae present from chaetiger 3 to posterior chaetigers, homogomph spinigers present throughout, anchylosed falcigers present from chaetiger 12 to posterior end with three anchylosed falcigers on anterior chaetigers, two on mid-body chaetigers and one along posterior chaetigers. Neurochaetae dorsal fascicle: homogomph spinigers present throughout, heterogomph spinigers present on chaetigers 1–4, short-bladed heterogomph falcigers with recurved tip and serrations present throughout except chaetigers 1–4. Neurochaetae ventral fascicle: heterogomph spinigers present on chaetigers 1–4 and mid-body to posterior chaetigers, short-bladed heterogomph falcigers with recurved tip and serrations present throughout except chaetigers 1–4 (Fig. 6A–F). Type locality: Jihuei, Taitung City, Taiwan. Distribution: Known only from the type locality. Remarks: Platynereis jihueiensis sp. nov. is similar to P. bicanaliculata (Baird, 1863) and P. shihmenensis sp. nov., which have bifid tip of notopodial anchylosed falcigers (Imajima 1972: 77–78, fig. 18i; Sun and Young 2004: 212, fig. 122H; Fig. 6B). However, P. jihueiensis sp. nov. differs from P. bicanaliculata by having: 1) one to two parallel transverse rows of pectinate paragnaths in Area III (versus a broad oval patch); 2) six to seven parallel transverse rows and one oblique row of pectinate paragnaths in Area IV (versus a crescentic group of four or five rows); 3) seven groups of pectinate paragnaths, middle groups each with three parallel transverse rows and two outer most groups each with one or two paragnaths in Areas VII–VIII (versus seven groups, each group with two transverse rows); and 4) dorsal cirrus shorter than dorsal ligule in Fig. 6. Platynereis jihueiensis sp. nov.; holotype (NMNS 8390-3): A, notochaeta, homogomph spiniger, chaetiger 50; B, notochaeta, anchylosed falciger, chaetiger 30; C, neurochaeta of dorsal fascicle, homogomph spiniger, chaetiger 50; D, neurochaeta of dorsal fascicle, short-bladed heterogomph falciger, chaetiger 50; E, neurochaeta of ventral fascicle, heterogomph spiniger, chaetiger 69; F, neurochaeta of ventral fascicle, shortbladed heterogomph falciger, chaetiger 50. Scale bars: A–F = 0.01 mm. page 8 of 13Zoological Studies 61:30 (2022) © 2022 Academia Sinica, Taiwan posterior chaetigers (versus longer than dorsal ligule) (Imajima 1972: 77–78, fig. 18d, h; Fig. 4C, D, F). The morphological differences between P. jihueiensis sp. nov. and P. shihmenensis sp. nov. are discussed below. Platynereis shihmenensis sp. nov. (Figs. 7A–C, 8A–F, 9A–F) urn:lsid:zoobank.org:act:2DFD4A22-7215-4F0A-A01B323223F7F76E Material examined: Holotype: NMNS8390-4, Shihmen (25°17.84'N 121°34.23'E), New Taipei City, Taiwan, intertidal rocky habitats, coll. P.-W. Hsueh, 2 Nov. 2003. Etymology: The name is derived from the name of the nearby village, Shihmen, where the worm was collected. Diagnosis: Platynereis with longest tentacular cirri reaching chaetiger 9. Light brown jaws, each with 5–6 lateral teeth; paragnath pattern: I = 0; II = 0; III = 0; IV = 4 parallel transverse rows and one oblique row of pectinate paragnaths toward jaws (left), 4 parallel transverse rows and one oblique row of pectinate paragnaths toward jaws (right); V = 0; VI = 3 nonparallel rows of pectinate paragnaths (left), 4 nonparallel transverse rows of pectinate paragnaths (right); VII–VIII = 5 groups of parallel transverse rows of pectinate paragnaths, middle groups each with 1–2 rows and 2 outer most groups each with 1 paragnath. Notopodial prechaetal lobe present throughout. Neuropodial postchaetal lobe present throughout. Notochaetae with homogomph spinigers throughout, anchylosed falciger present from chaetiger 11 to posterior end with one anchylosed falciger on each chaetiger throughout. Neurochaetae with homogomph spinigers throughout; dorsal fascicle with heterogomph spinigers on chaetigers 1–4, short-bladed heterogomph falcigers with recurved tip and serrations present throughout except chaetigers 1–4; ventral fascicle with heterogomph spinigers on chaetigers 1–4 and midbody to posterior chaetigers, short-bladed heterogomph falcigers with recurved tip and serrations present throughout except chaetigers 1–4. Description: Holotype complete, 37.0 mm long, 75 chaetigers, chaetiger 10 width 1.5 mm, excluding parapodia; beige in alcohol (Fig. 7A–B). Prostomium longer than wide, lateral antennae as long as palps; palpophores globose, palpostyles conical, four pairs of Fig. 7. Platynereis shihmenensis sp. nov.; holotype (NMNS 8390-4): A, whole animal; B, anterior body; C, close-up of Area IV, right side; C, closeup of Area VI. Scale bars: A = 2.0 mm; B = 1.0 mm; C–D = 0.1 mm. page 9 of 13Zoological Studies 61:30 (2022)