Leiocapitella fujianensis, Lin & García-Garza & Wang, 2019

Lin, Junhui, García-Garza, María E. & Wang, Jianjun, 2019, First record of the genus Leiocapitella (Annelida: Capitellidae) from China with description of a new species, Zootaxa 4604 (1), pp. 191-196 : 193-194

Leiocapitella fujianensis sp. nov.

Figs 1 A–G, 2A–C

Material examined. Holotype, TIO-BTS-Poly-104, one specimen, water off Fujian Province, the continental shelf of the East China Sea, [25°58′19″N, 120°30′06″E], 64 m, mud, incomplete, coll. J H Lin, 21 December 2007.

Comparative material examined. Holotype Leiocapitella glabra , ( LACM-AHF POLY 0425 ) and 1 Paratype ( LACM-AHF POLY 0205 ). 1 mile northwest of San Gabriel Bay , Espíritu Santo Island , Gulf of California , México, stn. 1107-40 [24°26'39"N, 110°22'53"W to 24°26'19"N, 110°22'45"W], 8–10 m, 13 February 1940, Allan Hancock Pacific Expedition of 1940, Velero III ; Paratype, 2 miles southwest of Cedros Islands light, stn. 1265–41 [28°20'33"N, 115°10'10"W to 28°20'45"N, 115°09'45"W], 16 m, 28 February 1941, Allan Hancock Pacific Expedi- tion of 1941, Velero III, in soft bottom .

Description. Holotype incomplete ( Figs 1 A–C, 2A), anterior fragment with 80 chaetigers, 44.5 mm long by 0.9 mm wide (maximum width at chaetiger 3). Body thread-like. Thorax flattened ventrally, dorsally round. Color in alcohol tan, except dark tan on chaetigers 4–12 ( Figs 1 A–B, 2A). Thoracic epithelium smooth. Prostomium rounded at tip. Peristomium slightly wider than long, 1.5 times as long as first chaetiger. Eyespots present, concealed by peristomium. Proboscis retracted.

Thorax with 14 chaetigers. First chaetiger uniramous, with capillaries in notopodium only ( Figs 1 A–C, 2A). Intersegmental grooves conspicuous in thorax and chaetigers 8–13 biannulated ( Figs 1 A–B, 2A). Thoracic segments increasing in width from peristomium to a maximum at chaetiger 3, then gradually tapering to end of thorax. Thoracic chaetigers about 2.5 to 4 times as wide as long. Notopodia dorso-lateral in anterior thorax, moving dorsally gradually to end of thorax; neuropodia lateral throughout. Chaetigers 2–13 with only capillaries in both rami. Chaetiger 14 transitional with notopodial capillaries and neuropodial hooks ( Fig. 1A, D ). Chaetal fascicles situated just posterior to mid-segment. Number of capillaries ranging from 10–15 per fascicle. Lateral organs present on thoracic chaetigers as small pore, located between noto- and neuropodia but closer to notopodia ( Fig. 1B, D ); those in abdomen indistinct. Four pairs of genital pores occur in intersegmental grooves between chaetigers 7/8, 8/9, 9/10, and 10/11.

Transition between thorax and abdomen marked by increased length of abdominal segments and change in chaetal arrangement ( Fig. 1A, D ). Anterior abdominal segments longer but narrower than posterior thoracic segments. Length about 0.6 times width on first abdominal chaetiger ( Fig. 1A ), increasing to 1.5 times width in midabdomen, then decreasing to 0.8 times width in posterior segments ( Fig. 1E ). Parapodial lobes slightly swollen and well separated throughout abdomen. Gap between notopodial lobes of same chaetiger shorter than between notopodium and neuropodium. Chaetal fascicles positioned on posterior 1/4 of segments in anterior abdomen to near posterior edge of segments posteriorly ( Fig. 1E ). All abdominal segments with only hooded hooks. Parapodial lobes with approximately 20 hooks per fascicle, more in neuropodia. Notopodial and neuropodial abdominal hooded hooks similar along body, with angled node, distinct constriction, developed shoulder, and short hood; posterior shaft curved, longer than anterior shaft, attenuated to terminal end ( Fig. 1F ). Hooks with seven teeth in three rows above main fang ( Figs 1G , 2 B–C): basal row with two large teeth, middle row with a larger median tooth, superior row with four small teeth. Main fang subtriangular, longer than wide ( Fig. 1F, G ).

Branchiae not found. Pygidium absent.

Methyl green staining. Peristomium and first three chaetigers stained medium blue, with dense spots of stain. Darker stain on chaetiger 4–12. Thereafter, segments stained light blue ( Figs 1 A–B, 2A).

Distribution. Currently known only from water off Fujian Province, the continental shelf of the East China Sea.

Ecology. The surface sediment was characterized by mud. Water depth was 64 m.

Etymology. The specific name is derived from the type locality, Fujian Province.

Remarks. Currently, the genus Leiocapitella includes four accepted species (Read & Fauchald, 2018b), i.e., L. atlantica , L. dollfusi , L. glabra , and L. hartmanae . Of these, L. dollfusi was first described as Mastobranchus dollfusi by Fauvel (1936) and transferred to the genus Leiocapitella by Bellan (1964), since the chaetal formula of M. dollfusi matched that of Leiocapitella . Based on the identical dentition of hooks and chaetal formula, some authors proposed L. dollfusi as a possible synonym of L. glabra ( Bellan, 1964; Ben-Eliahu & Fiege, 1995). Faulwetter et al. (2017) agreed with that. However, the palmate branchiae characteristic of L. dollfusi were not confirmed in L. glabra ( Ben-Eliahu & Fiege, 1995) . In this paper, we consider L. dollfusi as a valid species.

Leiocapitella fujianensis sp. nov. agrees with the amended definition of Leiocapitella ( Magalhães & Blake, 2017) in that it bears 13 thoracic chaetigers with only capillaries and a transitional segment on chaetiger 14. Among all Leiocapitella species, L. fujianensis sp. nov. resembles L. dollfusi from European waters and L. near glabra from Andaman Sea, Thailand by possessing only one transitional segment, which is located on chaetiger 14. However, the dentition of the hooded hooks has 7 teeth above main fang in L. fujianensis sp. nov. instead of 3 teeth as in L. dollfusi and L. near glabra . In the original description of L. dollfusi, Fauvel (1936) mentioned that notopodial branchiae reduced to a short nipple on each side of the tori and neuropodial tori almost touched each other in anterior abdomen, which are not observed in L. fujianensis sp. nov. We cannot confirm whether branchiae were present in posterior abdomen of L. fujianensis sp. nov. due to lack of posterior part. In addition, the methyl green stain was different on anterior thorax. The first three thoracic chaetigers stained medium blue with dense spots of stain in L. fujianensis sp. nov. in contrast to light green in L. near glabra . Although the original description showed that L. glabra has one transitional segment on chaetiger 14, re-examination of type material by Green (2002) indicated that L. glabra actually has two transitional segments on chaetigers 13–14 ( Fig. 2 D–E). This paper describes the first record of Leiocapitella , and L. fujianensis sp. nov. in Chinese waters. The distribution of the new species is unknown since the first record was based on one specimen.

Figures

FIGURE 1. Leiocapitella fujianensis sp. nov. A, anterior 18 chaetigers in lateral view B, chaetigers 1–7 in lateral view C, chaetigers 1–7 in ventral view, peristomium retracted into body when using a needle to fix anterior end D, chaetigers 9–16 in lateral view E, chaetigers 70–75 in dorso-lateral view F, abdominal hook from chaetiger 80 in lateral view G, dentition of posterior abdominal hook. Shading on A–B indicates methyl green staining pattern. Scale bar: A–E, 1mm; F, 10 μm; G, 2 μm.

FIGURE 2. Type materials of Leiocapitella fujianensis sp. nov. (A–C) and Leiocapitella glabra Hartman, 1947 (D–F). A, thorax and anterior abdomen, showing methyl green staining pattern B–C, hooded hooks of posterior abdominal chaetigers D– E, thorax and anterior abdomen F, hooded hooks.