Natsushima nanhaiensis, Hui & Lin & Perez & Qiu & Sun, 2024

Hui, Fan, Lin, Yi-Tao, Perez, Maeva, Qiu, Jian-Wen & Sun, Yanan, 2024, Positive association between PTN polymorphisms and schizophrenia in Northeast Chinese Han population., Zoological Studies 63 (41), pp. 141-149 : 4-7

Phylum Annelida Lamarck, 1802 Family Chrysopetalidae Ehlers, 1864 Genus Natsushima Miura & Laubier, 1990 Type species Natsushima bifurcata Miura & Laubier, 1990

Natsushima nanhaiensis n. sp. ( Figs. 1–2 ) urn:lsid:zoobank.org:act:7AE5F9DA-92A3-4285-8A47-81012767803D

Type specimens: Holotype and paratypes are deposited in the Tropical Marine Biodiversity Collections of the South China Sea ( TMBC), Chinese Academy of Sciences, Guangzhou under catalogue numbers TMBC 031043 (holotype) and TMBC 031044– TMBC 031047 (paratypes 1–4).

Type locality: Haima cold seep, 1383 m water depth, off southern Hainan Island, on the northwestern slope of the South China Sea.

Etymology: The species is named after Naihan, the Chinese name for the South China Sea. The Chinese name corresponding to the Latin name of this species is “ 南海松島蟲 ”.

Diagnosis: Body long, tapering posteriorly, flattened ventrally, arched dorsally. Prostomium short, with pair of antennae, no eyes. Parapodia subbiramous. Notopodia and neuropodia similar length, notoacicula absent. Neuropodia stout, with long neuroacicula, 2–6 hooks and numerous bifurcate chaetae with similar tooth length. Pygidium rounded, without anal appendages.

Description: Holotype 46 mm long, 2.7 mm wide including parapodia, 112 segments. Longest paratype 52 mm long, 2.0 mm wide with 175 segments ( Fig. S1 ). Holotype and all paratypes complete except paratype 2.

Body vermiform, flattened ventrally and arched dorsally, tapering anteriorly and posteriorly ( Fig. 1A– E ). Specimens preserved in alcohol pale, body surface smooth. Living specimens pink-red.

Prostomium oval, short, with pair of small antennae, without eyes ( Figs. 1D ; 2A–B ). Mouth located between prostomium and first chaetiger, without jaw ( Figs. 1E ; 2B ). First chaetiger partially fused to prostomium, with dorsal and ventral cirri, and numerous neuropodial chaetae ( Figs. 1C ; 2A–B ). Posterior segments similar in width as anterior segments ( Fig. 1A ). Pygidium simple, rounded, without anal cirri ( Figs. 1D ; 2F ).

Parapodia subbiramous throughout, notopodia conical, dorsal cirri well-developed, basally swollen and distally pointed, without notoacicula ( Fig. 1F ). Neuropodia stout, with short ventral cirri ( Fig. 2A, C–D ). Each neuropodium supported by single very long, straight and thick embedded neuroacicula with pointed tip ( Fig. 1F ). Neuropodia similar in length with notopodia in midbody parapodia ( Fig. 1B, F ).

Chaetae simple, consisting of stout hooks and smaller bifurcate chaetae. Hooks few (2–6), with long handle, slightly curved distal end and swollen subdistal knob ( Figs. 1G–H ; 2H ). Bifurcate chaetae numerous, located below hooks ( Figs. 1F, H ; 2A–E, G ). Distal teeth of bifurcate chaetae curved, height of two teeth approximately equal, one tooth slightly thinner and sharper than the other ( Figs. 1I–K ; 2I ). Middle segments with more hooks and bifurcate chaetae than anterior and posterior segments.

Distribution: Currently known only from the Haima cold seep.

Remarks: Three species ( N. bifurcata , N. graciliceps , N. sashai ) have been described in the genus Natsushima . Natshushima nanhaiensis n. sp. can be distinguished from its congeneric species by a combination of morphological characters of the chaetae and parapodia, such as the length, shape and number of neuropodial hooks. Natshushima nanhaiensis n. sp. has up to six neuropodial hooks per midbody neuropodium ( Fig. 1H ) while only two to four are present in the other Natsushima species: 3–4 in N. sashai , 2–4 in N. bifurcata , three in N. graciliceps ( Miura and Laubier 1990; Miura and Hashimoto 1996; Aguado and Rouse 2011). The hooks of N. nanhaiensis n. sp. are significantly longer and thinner than those of N. sashai , similar to those in N. bifurcata (considering the length between the distal tip and subdistal knob): those of N. sashai and N. graciliceps are ~18 and 13 µm, respectively, but those of N. bifurcata and N. nanhaiensis n. sp. are ~30 and> 35 µm, respectively ( Miura and Laubier 1990; Miura and Hashimoto 1996; Aguado and Rouse 2011).

The two teeth of the bifurcate chaetae are similar in length in N. nanhaiensis n. sp., N. bifurcata and N. graciliceps . In both N. nanhaiensis n. sp. and N. bifurcata , one tooth is slightly thinner and pointed while the other is thicker and distally blunt. However, in N. graciliceps , both teeth are similar in size ( Miura and Hashimoto 1996). In N. sashai , the two teeth are remarkably different, with one of them much thinner and shorter than the other, both with conspicuously pointed tips ( Aguado and Rouse 2011).

In both N. nanhaiensis n. sp. and N. sashai , the notopodia and the neuropodia are similar in length in each parapodium. By contrast, in N. bifurcata the notopodia are shorter than the neuropodia, whereas in N. graciliceps , the notopodia are more than twice as long as the neuropodia. Among the four Natsushima species, N. bifurcata , N. sashai , and N. nanhaiensis originate from cold seeps, while the type of chemosynthetic environment (cold seep or hydrothermal vent) in Kagoshima Bay was not recorded for N. graciliceps ( Miura and Laubier 1990; Miura and Hashimoto 1996; Aguado and Rouse 2011). N. bifurcata was collected from the mantle cavity of Acharax johnsoni , which was misidentified as a species of the genus Solemya in the original description ( Miura and Laubier 1990; Miura and Hashimoto 1996). On the other hand, the other three species were found among the gill lamellae in the mantle cavity of their hosts (both N. sashai and N. nanhaiensis inhabit Acharax sp. specimens, while N. graciliceps was found in Solemya ) ( Miura and Hashimoto 1996; Yang 2007; Aguado and Rouse 2011).

Figures

Fig. 1. Natsushima nanhaiensis n. sp. A–B, D, F–G, holotype (TMBC031043); C, E, paratype 3 (TMBC031046). A, whole specimen, dorsal view; B, midbody segments, ventral lateral view; C, anterior end, dorsal view; D, posterior end, ventral view; E, anterior end, ventral view; F, midbody parapodium, posterior view; G–H, midbody ventral hooks; I–K, ventral bifurcate chaetae. Abbreviations: no, notopodia; ne, neuropodia; nh, neuropodial hooks; bc, bifurcate chaetae; dc, dorsal cirri; nla, neuroacicula. Scale bars: A–E = 1000 μm; F = 100 μm; H = 50 μm; G, I–K = 10 μm.

Fig. 2. Natsushima nanhaiensis n. sp. A, C, F–I, paratype 4 (TMBC031047); B, D, paratype 1 (TMBC031044); E, paratype 3(TMBC031046). A–B, anterior end, ventral view; C, posterior parapodia, ventral view; D, anterior segments parapodia, ventral view; E, midbody segments ventral chaetae; F, posterior end, ventral view; G, posterior parapodia, dorsal view; H, ventral hook; I, ventral chaetae. Abbreviations: ne, neuropodia; dc, dorsal cirri; vc, ventral cirri; an antenna. Scale bars: A, C–D, F = 100 μm; B, E = 30 μm; G = 10 μm; H–I = 3 μm.