Tetranchyroderma schizocirratum Chang, Kubota & Shirayama, 2002

Lee, Jimin, Kim, Dongsung & Chang, Cheon Young, 2013, Description of three new Tetranchyroderma gastrotrichs (Macrodasyida: Thaumastodermatidae) from South Korea, Zootaxa 3709 (5), pp. 483-493 : 491-493

Tetranchyroderma schizocirratum Chang, Kubota & Shirayama, 2002

( Fig 4 )

Tetranchyroderma schizocirratum Chang, Kubota & Shirayama, 2002 , p. 770, figs. 1, 2.

Material examined. 3 inds, Hyeobje beach, Jeju I., 10 Aug. 1997, leg. H.S. Rho & J.W. Choi; 7 inds., Biando I., 25 Nov. 2000, leg. J. Lee & C.Y. Chang; 5 inds., Daejeong, Jeju I., 3 Apr. 2002, leg. J. Lee & U.H. Kwon; 5 inds., Seongsan, Jeju I., 24 Jan. 2003, leg. J. Lee, J.M. Jeon & C.Y. Chang; 4 inds., Yongdu beach, Boryeong, 13 July 2003, leg. J. Lee & C.Y. Chang.

Description. Body oblong, Lt 309 µm; both sides nearly parallel, weakly constricted in pharyngeal region. Widths of head/PhJIn/trunk/caudal base 51/43/57/34 µm at U06/U37/U58/U93, respectively.

Head protruding, with its anterior border undulating and with numerous sensory hairs. A pair of pestle organs located dorsolaterally at U07, each accompanied by a sensory bristle.

Epidermal glands 4 per side, arranged from mid-pharyngeal region to posterior intestinal region (U20–U75), different in size (10–16 µm in diameter) with generally circular shape containing granules.

Cuticular armature with tetrancres only, arranged in 13–16 columns in mid-trunk region, each column comprising about 55–61 ancres; each tine of tetrancres similar in length; ancres 14 µm long in diagonal length between opposite tines at mid-trunk region, but smaller on both anterior part of oral hood and caudal base.

Four pairs of dorsolateral cirratum-type tubes located from just behind PhJIn to posterior trunk region at U39, U63, U77 and U86, respectively; last one long and robust, with its distal portion bifurcate.

Adhesive tubes: TbA, 6–7 per side, comprising a medial tube and 5–6 ventrolateral tubes forming an arc. TbVL, 15–17 per side, anterior 2 tubes, including a cirratum-type tube, in pharyngeal region and others in intestinal region at U38–U69; eighth tube with a small cirratum-type tube issuing together at its base. A pair of foot-type TbV, each consisting of 3 tubes at U80. TbP, 12 per side, forming pedicles with 2 distal tubes and 1 dorsal cirratumtype tube; flanked with 6 lateral tubes and 3 medial ones.

Reproductive system: simultaneous hermaphrodite, testis reaching to U41, behind PhJIn; copulatory organ small, pyriform located in U78–U87. Seminal receptacle small, suboval in front of copulatory organ. Two ova located in mid-intestinal region.

Remarks. This species was first recorded from subtidal sands at Shirahama, Japan by Chang et al. (2002). Korean specimens agree well with the original description, especially in having the last pairs of dorsolateral cirratum-type tubes with cleft at distal part. However, Korean specimens show some differences from the original description in possessing four dorsolateral cirratum-type tubes per side, including an additional tube issued between second and third. Moreover, Korean specimens have more adhesive tubes such as 6–7 TbA per side, 14– 16 TbVL per side at intestinal region and 5–6 lateral TbP per side.

Korean specimens were collected from fine to medium sands in the subtidal bottom (3–5 m deep) of the Yellow Sea coast and around Jeju Island.

Figures

FIGURE 4. Tetranchyroderma schizocirratum Chang, Kubota & Shirayama. A, habitus, dorsal view; B, habitus, ventral view. Scale bar = 50 µm.