Halechiniscus churakaagii, 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 : 153-155

Taxon classification Animalia Arthrotardigrada Halechiniscidae

Halechiniscus churakaagii sp. n. Figs 4, 5, Table 2

Diagnosis.

Halechiniscus with cephalic region consisting of antero-medial lobe and dorsal lobe; median cirrus inserted on long robust cirrophore; dorsal internal cirrus inserted on robust cirrophore; ventral external cirrus inserted on short cirrophore; lateral cirrus and primary clava inserted on large lateral cirrophore; large scapular process with flat oval tip; cirrus E with proximal portion with distal dark portion and distal flagellum; bipartite leg I sense organ; large, unsegmented legs II and III sense organs; papillate leg IV sense organ; all claws with calcar.

Material examined.

Holotype: KUZ Z710: adult female found in sediment sample 1 (Table 1).

Paratype: KUZ Z711: adult female found in sediment sample 4 (Table 1).

Type locality.

Water depth of 6 m, off Sedake, Oura Bay, Okinawajima, one of the Ryukyu Islands, Japan (26°32'39.06"N, 128°2'52.8"E). Collected by the author on 24th January 2014.

Type depository.

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

Description of holotype.

Adult female, body length: 170 μm (Figs 4, 5A, B). Dorsal and ventral surface smooth. Cephalic region divided into two lobes: antero-ventrally protruded round medial lobe and dorsal lobe. Unpaired median cirrus with scapus (42 μm) constricted at distal end, tubular portion (20 μm) and flagellum (4 μm) inserted on robust cirrophore (28 μm); positioned dorsally 28 μm from frontal margin on dorsal lobe. Pair of internal cirri each with scapus (16 μm), tubular portion (16 μm) and flagellum (5 μm) inserted on cirrophore; positioned dorsally on basal margin of medial lobe. Base of internal cirri arise postero-internal to base of scapi beneath cuticle. Pair of external cirri each with scapus (9 μm), tubular portion (9 μm) and flagellum (4 μm) inserted on cirrophore; positioned ventrally on medial lobe. Base of external cirri arise posterior to scapi beneath cuticle. Lateral cirrus with scapus (35 μm), tubular portion (23 μm) and flagellum (10 μm) and elongate primary clava (34 μm) inserted on each large, lateral cirrophore; positioned slightly anterior to level of median cirrus on dorsal lobe. 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 (17 μm × 19 μm). Laterally protruded scapular process (42 μm) with flat oval tip (Figs 4, 5C). No other process present. Cirrus E (86 μm) segmented into proximal portion and distal flagellum. Under phase contrast microscopy distal end of proximal portion appears dark (Fig. 5D). This could be a distinct portion with accordion-like folds but scanning electron microscopy is required for confirmation. Rosette-like female gonopore opens ventrally 20 μm anterior to anus. Seminal receptacle ducts open postero-lateral to gonopore. Vesicles of seminal receptacles not visible. Leg I sense organ (11 μm) consists of scapus and flagellum. Leg II and III sense organs (36 μm, 32 μm) each consists of unsegmented, large spine. Papillate leg IV sense organ (16 μm) with basal van der Land’s body and terminal constriction inserted on slender cirrophore. Each leg terminates in digits with wrinkles and distal claws. All claws with small calcar.

Etymology.

The specific epithet, churakaagii, is a Ryukyuan word for "beautiful woman" ( Tojo 1930) referring to the well-defined cephalic morphology of the new species.

Differential diagnosis.

The robust cirrophores of the median and lateral cirri are present in Halechiniscus chafarinensis De Zio Grimaldi & Villora Moreno, 1995, Halechiniscus macrocephalus Grimaldi de Zio, D’Addabbo Gallo & Morone De Lucia, 1988, Halechiniscus paratuleari Grimaldi de Zio, D’Addabbo Gallo & Morone De Lucia, 1988, Halechiniscus tuleari Renaud-Mornant, 1979 and Halechiniscus churakaagii sp. n. Among these species, Halechiniscus paratuleari and the new species are the only species with large scapular processes. The new species is distinguished from Halechiniscus paratuleari by the flat oval tip of the scapular process, which is acute in the latter and by the dark portion on cirrus E, which is absent in the latter.

I have interpreted the dorsally positioned cirrus as internal cirrus and the ventrally positioned cirrus as external cirrus in the new species, which is opposite to the interpretation of these features in the original descriptions of Halechiniscus tuleari and Halechiniscus paratuleari .