Halechiniscus yanakaagii, Fujimoto, Shinta, 2015

Fujimoto, Shinta, 2015, Halechiniscidae (Heterotardigrada, Arthrotardigrada) of Oura Bay, Okinawajima, Ryukyu Islands, with descriptions of three new species, ZooKeys 483, pp. 149-166 : 155-158

Taxon classification Animalia Arthrotardigrada Halechiniscidae

Halechiniscus yanakaagii sp. n. Figs 6, 7, Table 2

Diagnosis.

Halechiniscus with no distinct cephalic lobes; only lateral cirrus and primary clava inserted on cirrophore; laterally protruded arched, double processes with acute tips at level of leg I; unsegmented cirrus E; bipartite leg I sense organ; unsegmented legs II and III sense organs; papillate leg IV sense organ; claws of internal digits with dorsal spur.

Material examined.

Holotype: KUZ Z712: adult female found in sediment sample 5 (Table 1).

Type locality.

Water depth of 6 m, Off Thima, Oura Bay, Okinawajima, one of the Ryukyu Islands, Japan (26°32'0.81"N, 128°3'49.61"E). Collected by the author on 28th January 2014.

Type depository.

The holotype is deposited in the Zoological Collection of Kyoto University (KUZ).

Description of holotype.

Adult female, body length: 170 μm (Figs 6, 7A). Dorsal and ventral surface smooth. Cephalic region not divided into distinct lobes. Tubular portions of cephalic cirri indistinct from flagellum for median, internal and external cirri. Unpaired median cirrus with scapus (11 μm) and flagellum (24 μm); inserted dorsally 16 μm from frontal margin. Pair of internal cirri each with scapus (6 μm) and flagellum (20 μm); inserted dorsally close to frontal margin. Pair of external cirri each with scapus (7 μm) and flagellum (11 μm); inserted ventrally close to frontal margin. Lateral cirrus with scapus (11 μm), tubular portion (22 μm) and flagellum (8 μm) and elongate primary clava (21 μm); inserted on each lateral cirrophore positioned at same level as median cirrus. Primary clava with basal van der Land’s body inserted antero-ventrally to lateral cirrus. Secondary clava absent. Mouth cone protruded antero-ventrally. Bucco-pharyngeal apparatus not visible except for pharyngeal bulb (14 μm × 20 μm). Laterally protruding arched, double processes (23 μm, 26 μm) with acute tip situated dorsally at level of leg I (Figs 6, 7B). Unsegmented cirrus E (41 μm) inserted on short cirrophore. Rosette-like female gonopore present. Seminal receptacles not visible. Leg I sense organ (14 μm) consists of tapering spine and distal flagellum. Leg II and III sense organs (both 21 μm) each consists of unsegmented spine. Papillate Leg IV sense organ (15 μm) with basal van der Land’s body inserted on small cirrophore. Each leg terminates in digits with wrinkles and distal claws. Claws of internal digits with dorsal spur.

Etymology.

The specific epithet, yanakaagii, is a Ryukyuan word for "ugly woman" ( Tojo 1930) referring to dirty appearance of the holotype.

Differential diagnosis.

Halechiniscus yanakaagii sp. n. and Halechiniscus tuleari are the only two Halechiniscus species with double processes at the level of leg I. The new species is distinguished from Halechiniscus tuleari by the absence of distinct cephalic lobes and robust cephalic cirrophores (which are present in the latter species), the similar length, arched, double processes (23 μm, 26 μm) in contrast with a short, straight, anterior process (holotype female: 8 μm; paratype male: 4 μm) and a long, straight, posterior process (holotype female: 19 μm; paratype male: 10 μm) (see: Renaud-Mornant 1979), and the absence of processes at level of leg II and III, which are present in Halechiniscus tuleari .