Three new species of Sternaspidae (Annelida: Sedentaria) from Thailand Author Plathong, Jintana 0000-0003-3473-1680 Marine Ecosearch Management Co., Ltd., 4 / 31 Moo 1, Namnoi, Hat Yai, Songkhla, 90110, Thailand. & Marine Science Learning Center, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand. sakanan 2004 @ yahoo. com; https: // orcid. org / 0000 - 0003 - 3473 - 1680 sakanan2004@yahoo.com Author Plathong, Sakanan 0000-0003-3473-1680 Marine Science Learning Center, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand. sakanan 2004 @ yahoo. com; https: // orcid. org / 0000 - 0003 - 3473 - 1680 sakanan2004@yahoo.com Author Salazar-Vallejo, Sergio I. 0000-0002-6931-0694 Depto. Sistemática y Ecología Acuática, El Colegio de la Frontera Sur, Chetumal, Quintana Roo, México. savs 551216 @ hotmail. com; https: // orcid. org / 0000 - 0002 - 6931 - 0694 savs551216@hotmail.com text Zootaxa 2021 2021-12-13 5081 3 373 388 journal article 2997 10.11646/zootaxa.5081.3.4 28190fde-35c3-4e10-b6a0-a45027518be0 1175-5326 5775763 241F3263-0DFB-4372-8CA8-1537BF9D0B91 Petersenaspis apinyae sp. nov. LSID urn:lsid:zoobank.org:act: 5083A547-AD34-4A1E-8328-1B49765744F8 Figs 3–4 Material examined. 43 specimens , all collected from 50–80 m deep in the offshore Petroleum Production Area , the Gulf of Thailand , Western Pacific ; mud mixed with sand and shells; coll. Marine Ecosearch Management Company ( MEM ). Holotype : PSUZC-POL-0268 ( 1 spec. ), GT-W ( 8°37’16”N , 101°46’27”E ), 23 Mar 2010 , 72 m. Paratypes : PSUZC-POL-0269 ( 1 spec. ), GT-SB ( 9°42’35”N , 101°19’09”E ), 8 Mar 2009 , 60 m; PSUZC-POL-0270 ( 1 spec. ), GT-PL ( 9°40’43”N , 101°23’09”E ), 11 Mar 2009 , 60 m; PSUZC-POL-0271 ( 1 spec. ), GT-H ( 9°38’23”N , 101°13’21”E ), 14 Mar 2009 , 60 m; PSUZC-POL-0272 ( 1 spec. ), GT-MK ( 8°33’48”N , 101°47’22”E ), 20 Mar 2009 , 80 m; PSUZC-POL-0273 ( 1 spec. on SEM stub), GT-U ( 8°23’02”N , 101°43’39”E ), 21 Mar 2009 , 80 m; PSUZC- POL-0274 ( 1 spec. ), GT-R ( 8°53’01”N , 101°31’56”E ), 20 Mar 2010 , 70 m; PSUZC-POL-0275 ( 1 spec. ), GT-T2-2 ( 8°54’16”N , 101°28’52”E ), 26 Apr 2011 , 72 m; PSUZC-POL-0276 ( 1 spec. ), GT-T2-1 ( 8°54’06”N , 101°29’01”E ), 27 Apr 2011 , 72 m; PSUZC-POL-0277 ( 1 spec. ), GT-T3 ( 8°33’52”N , 101°37’02”E ), 28 Apr 2011 , 72 m; PSUZC- POL-0278 (2 specs., 1 juvenile ), GT-UP ( 8°37’16”N , 101°46’27”E ), 1 Apr 2012 , 76 m; PSUZC-POL-0279 ( 1 spec. ), GT-L ( 9°06’15”N , 101°14’05”E ), 10 Jun 2015 , 50 m; PSUZC-POL-0280 ( 1 spec. ), GT-SG ( 9°23’13”N , 101°21’35”E ), 12 Jun 2015 , 50 m; PSUZC-POL-0281 ( 1 spec. ), GT-SF ( 9°25’09”N , 101°19’18”E ), 11 Jun 2015 , 50 m; PSUZC-POL-0282 ( 1 spec. ), GT-SA ( 9°17’37”N , 101°25’27”E ), 12 Jun 2015 , 50 m; PSUZC-POL-0283 ( 1 spec. , on SEM stub), GT-L-7 ( 9°06’43”N , 101°07’40”E ), 9 Sep 2015 , 64 m; PSUZC-POL-0284 ( 1 spec. ), GT-W2-19 ( 8°29’48”N , 101°42’46”E ), 9 Sep 2015 , 71 m; PSUZC-POL-0285 ( 1 spec. ), GT-W2-3 ( 8°29’39”N , 101°42’55”E ), 9 Sep 2015 , 71 m; PSUZC-POL-0286 ( 1 spec. ), GT-W2-11 ( 8°30’02”N , 101°42’32”E ) 10 Sep 2015 , 71 m; PSUZC- POL-0287 ( 1 spec. ), GT-R ( 8°53’04”N , 101°31’59”E ), 25 Jun 2016 , 69 m; PSUZC-POL-0288 ( 1 spec. , on SEM stub), GT-SF ( 9°25’18”N , 101°19’09”E ), 22 Jun 2018 , 69 m; PSUZC-POL-0289 ( 1 spec. , juvenile), GT-PG-23 ( 9°43’17”N , 101°22’26”E ), 3 Jul 2018 , 60 m; PSUZC-POL-0290 ( 1 spec. ), GT-PG-44 ( 9°42’48”N , 101°22’43”E ), 5 Jul 2018 , 60 m; AM W.52923 ( 1 spec. ), G4/43 REF ( 10°33’26”N , 100°48’03”E ) , 15 Apr 2011 , 60 m. Additional material: The offshore Petroleum Production Area, the Gulf of Thailand : 2 specs., GT-T2-3 ( 8°54’06”N , 101°29’01”E ), 23 Apr 2011 , 60 m; 1 spec. , GT-UB ( 8°28’24”N , 101°52’42”E ), 30 Mar 2012 , 76 m; 2 specs., GT-W ( 8°29’50”N , 101°42’43”E ), 30 Mar 2014 , 71.0 m; 2 specs., GT-UB ( 8°28’24”N , 101°52’42”E ), 9 Sep 2015 , 70 m; 1 spec. , GT-I ( 9°38’54”N , 101°12’55”E ), 11 Sep 2015 , 68 m; 1 spec. , GT-PM-23 ( 9°45’28”N , 101°17’59”E ), 3 Jul 2018 , 73 m; 1 spec. , GT-R ( 8°53’02”N , 101°31’56”E ), 28 Mar 2019 , 70 m; 4 specs., GT-Q, 30 Mar 2019 ,70 m; 1 spec. , GT-Q-38 ( 8°55’59”N , 101°35’26”E ); 1 spec. , GT-Q-50 ( 8°56’00”N , 101°35’17”E ); 1 spec. , GT-Q-6 ( 8°56’09”N , 101°35’19”E ); 1 spec. , GT-Q-8 ( 8°56’10”N , 101°35’13”E ). Type locality. Gulf of Thailand , offshore petroleum concession area ( Fig. 2 ) . Description. Holotype complete without sediment particles; body 9.2 mm long, 3.7 mm wide, abdomen 7.0 mm long, about 20 segments, whitish in alcohol ( Fig. 3A–B ). Abdominal papillae thin, long. Paratypes , 13 specimens complete with exposed anterior region: 11 specimens mature, body 4.0– 12.6 mm long, 1.8–3.5 mm wide, abdomen 2.7–4.2 mm long, about 20 segments: 2 specimens juvenile, body 2.0– 2.3 mm long, 0.8 mm wide, abdomen 1.5–1.6 mm long. Eight specimens with introvert invaginated; body 5.4–8.3 mm long, 2.7–4.2 mm wide, and abdomen 5.2–6.7 mm long. Prostomium rounded (not completely exposed in holotype but fully exposed in some paratypes ); peristomium rounded, with short papillae extended behind prostomium. Mouth circular with papillae extending from base of prostomium to anterior edge of first chaetiger ( Figs 3C , 4A–B ). First three chaetigers with 11–16 large golden spatulate hooks and small golden spatulate hooks with up to 11 hooks, without subdistal dark areas ( Figs 3A–C , 4A–D ). Genital papillae short, conical, protrude ventrally from body wall between segments 7 and 8 ( Figs 3A–B , 4A–D ). Pre-shield region of eight segments ( Fig. 3A–B ), with single lateral bundles of 2–4 (mostly 3) short thin capillary chaetae ( Fig. 4E ) protruding from body wall along segments 8–14. Paratype with capillaries along chaetigers 8–15. Body papillae along dorsal and ventral surfaces small, minute; lateral papillae long, thin ( Fig. 4F–G ). Ventro-caudal shield with sediment particles and abundant, fine, long papillae; shield wider than long, butterfly wing-shaped, orange to reddish, integument without ciliary clumps; suture extended throughout shield. Shield without well-developed ribs and concentric lines. Anterior margins angular, anterior depression shallow. Anterior keels exposed. Lateral margins strongly curved, expanded anteriorly, reduced medially to posterior. Posterior shield wide and slightly curved. Fan with a median notch and two lateral notches. Median notch shallow ( Figs 3A, E–J , 4D, G–H ). Juvenile ventro-caudal shield yellowish with anterior and lateral margins rounded, fan with a median notch and smooth margin. Peg chaetae absent. Chaetal fascicles on marginal shield include 10 lateral fascicles, chaetae of each fascicle in offset and parallel arrangement, no concentric lines, and 12 posterior fascicles, 7 with 3–4 chaetae each (1–2 fine capillary chaetae) and 5 in lateral notch with about 3 delicate and very long capillary chaetae. The long fine chaetae are located at both sides of the lateral notch, near lateral chaetae, longer than abdomen region, or about 3 times as long as posterior chaetae. These chaetae are fragile, some broken in every specimen, about 3–5 intact chaetae instead of 15. Branchial filaments abundant ( Figs 3A–B, E , 4F, H ), consisting of two parts; the first part is the branchial body, coiled, the second a long filament with bloated posterior ( Figs 3A–B , 4H, F, I ), the base of branchial body connected to branchial plate. Branchial plates with long papillae and sediment particles ( Fig. 3D ). The anterior branchial body can retract leaving the long filament exposed. The branchia and filament are connected by a small ring ( Fig. 4K ). Branchiae are whitish, neither smooth nor covered with cilia ( Fig. 4L ), and the filament holder is golden or brownish, smoother than the branchia and composed of small rings ( Fig. 4M ), the posterior end is bloated with larger rings. The outer surface of each posterior ring is embossed with a row of ovoid shapes and tips roughly resembling the pads of a gecko’s feet. Their tips are often swollen and have a tapered end ( Fig. 4J ). They might possibly help by sucking or sticking to adjacent sediment particles to support the body. Variation. Juveniles with body wall and ventro-caudal shield very thin, transparent; shield light yellow to light brown. Adults with thicker body wall and harder shields. FIGURE 3. Petersenaspis apinyae sp. nov. Light photographs (A, B, E. Holotype PSUZC-POL-0268; C, F. PSUZC-POL- 0276; D. PSUZC-POL-0277; G. PSUZC-POL-0284; H. PSUZC-POL-0274; I. PSUZC-POL-0281; J. PSUZC-POL-0286). A. Complete specimen, dorsal view; B. Same, lateral view; C. Prostomium, frontal view; D. Branchial plate after removal of branchial and interbranchial filaments, ventral view; E–F. Ventro-caudal shield, oblique lateral view; G–J. Same, frontal view. Abbreviations: number of segments 1–15, anterior keel ak, branchial filament br, genital papilla gp, straight filament hd, mouth mo, peristomium pe, prostomium pr, suture st. FIGURE 4. Petersenaspis apinyae sp. nov. (A, C, D–F, I–K. PSUZC-POL-0273; B, L–N. PSUZC-POL-0283; H. PSUZC- POL-0288). A. Anterior region, ventral view. B. Anterior end, frontal view; C. Spatulate neurohooks, lateral view; D. Close up of smaller chaetae in rectangle of C.; E. Lateral simple chaetae of abdomen arrow points to capillary chaeta, lateral view; F. Posterior region, area in oval with lateral papillae, lateral view; G. Same, close up of oval area of F., lateral body surface; H. Ventrocaudal shields, frontal view; I. Posterior end, elongated papillae of lateral body in circle, lateral view; J. Branchiae and straight filament, lateral view; K. Ring at the connection between branchia and filament, top view; L. Close up texture of branchia, top view; M. Close up, filament surface; N. Close up, tip of posterior filament. Abbreviations: branchial filament br, capillary chaeta cc, straight filament hd, lateral capillary chaeta lcc, mouth mo, papilla pa, peristomium pe, prostomium pr. Etymology. The species name is in recognition of Mrs. Apinya Sukolra of the SEM section, Office of Scientific Instrument and Testing (OSIT), Prince of Songkla University, for her assistance with SEM photographs of polychaetes during the last 4 years. Habitat. Found at 50–80 m depth, in muddy sediments mixed with sand and shells, offshore Gulf of Thailand . Distribution. Only known in the offshore Petroleum Production Area, Gulf of Thailand ( Figs 1 , 2 ). Remarks. Petersenaspis apinyae sp. nov. resembles P. palpallatoci Sendall & Salazar-Vallejo, 2013 , P. narisarae sp. nov. , and P. pakbaraensis sp. nov. in having homogenously pigmented shields and both a median notch and two lateral notches. However, P. apinyae sp. nov. has more introvert hooks and posterior chaetae than P. palpallatoci with 20–22 introvert hooks per fascicle and 12 fascicles of posterior shield chaetae. P. palpallatoci has about 12–14 introvert hooks and 10 fascicles of posterior shield chaetae ( Sendall & Salazar-Vallejo 2013 ). Moreover, P. apinyae sp. nov. has a butterfly wing-shaped shield with lateral margins strongly curved and expanding anteriorly; and more lateral abdomen chaetae than P. palpallatoci , with up to 3 simple chaetae per bundle from segment 8–15. In P. palpallatoci , lateral shield margins are rounded, and there are only 2 simple lateral abdominal chaetae per bundle from segment 9–10 ( Sendall & Salazar-Vallejo 2013 ). Petersenaspis apinyae sp. nov. differs from P. pakbaraensis sp. nov. by having 20–22 spatulate hooks per fascicle whereas P. pakbaraensis sp. nov. has 13–19. P. apinyae sp. nov. , unlike P. pakbaraensis sp. nov. , does not have ciliary clumps, and the median notch is narrower and shallower than in P. pakbaraensis . The posterior shield is wide and slightly curved, whereas the posterior shield of P. pakbaraensis sp. nov. is narrow, protruding and strongly curved. Petersenaspis apinyae sp. nov. differs from P. narisarae sp. nov. by having a homogenously pigmented shield whereas P. narisarae has colored bands on its shield. Also, the abdomen of P. apinyae sp. nov. is not expanded.