Florarctus wunai, 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 : 150-153

Taxon classification Animalia Arthrotardigrada Halechiniscidae

Florarctus wunai sp. n. Figs 2, 3, Table 2

Diagnosis.

Florarctus with smooth dorsal cuticle; six alae with continuous caestus; frontal ala with no caestus; antero-lateral alae caestus with small projection at levels of leg I and II and developed projection at posterior end; postero-lateral alae caestus with parallelogram-shaped projection at posterior end; caudal ala divided into four lobes; caudal alae caestus with pair of small projections; longitudinally elongate secondary clava with internally directed weak swelling.

Material examined.

Holotype: KUZ Z705: adult female found in sediment sample 3 (Table 1).

Paratypes: KUZ Z706: adult female found in sediment sample 2 (Table 1); KUZ Z707: adult male found with holotype; KUZ Z708: four-clawed specimen of undetermined status found from sediment sample 5 (Table 1); KUZ Z709: four clawed juvenile found from sediment sample 2 (Table 1).

Type locality.

Water depth of 6 m, off Camp Schwab, Oura Bay, Okinawajima, one of the Ryukyu Islands, Japan (26°31'51.78"N, 128°3'10.74"E). Collected by the author on 25th January 2014.

Type depository.

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

Description of holotype.

Adult female, body length: 257 μm, excluding alae (Fig. 2A, 3A). Cephalic region clearly separated from trunk. Dorsal surface smooth with folds. Ventral surface smooth. Lateral margin of body surrounded by aliform expansions with continuous caestus, which consists of frontal ala, pair of antero-lateral alae, pair of postero-lateral alae and caudal ala. Frontal ala spreads across entire anterior margin of cephalic region. Scapi of internal cirri continuous with ala. Base of lateral cirri and primary clavae enveloped together in ala. Antero-lateral ala spreads from approximately level with median cirrus to level of leg III with four slight indentations. Antero-lateral alae caestus with small projections at level of leg I and leg II and developed projection at posterior end. Slightly overlapping antero-lateral ala, postero-lateral ala spreads from level of leg III to level of cirrus E with two indentations: anterior slight indentation and posterior relatively strong indentation. Postero-lateral alae caestus with developed projection parallelogram-shaped at posterior end. Caudal ala spread between pair of cirri E with pair of lateral indentations (26 μm deep) and medial indentation (40 μm deep). Caudal caestus with pair of small projections. Unpaired median cirrus (36 μm) with scapus (10 μm), tubular portion (22 μm) and flagellum (4 μm) inserted dorsally 27 μm from frontal margin. Pair of internal cirri (46 μm) each with scapus (13 μm) tubular portion (30 μm) and flagellum (3 μm) inserted at anterior margin. Internal structure of internal cirrus arise 25 μm from frontal margin. Pair of external cirrus (44 μm) with scapus (18 μm), tubular portion (20 μm) and flagellum (6 μm) inserted ventrally 30 μm from frontal margin. Internal structure of external cirrus arise 39 μm from frontal margin. Lateral cirrus (43 μm) with scapus (15 μm), tubular portion and flagellum and primary clava arise from same cirrophore. Boundary between tubular portion and flagellum of lateral cirrus indistinct in holotype. Lateral cirrus inserted dorso-posteriorly to primary clava. Primary clava (101 μm) thicker near base with basal van der Land’s body. Secondary clavae in shape of longitudinally elongated, flat sac with internally directed weak swelling on each side of ventrally protruded mouth cone (Figs 2B, 3B). Bucco-pharyngeal apparatus not visible except for pharyngeal bulb (32 μm × 24 μm). No bacterial vesicles visible. Leg I sense organ (29 μm) consists of tapering spine and distal flagellum. Leg II and leg III sense organ (28 μm and 24 μm respectively) each consists of unsegmented tapering spine. Leg IV sense organ (29 μm) consists of tapering spine with basal van der Land’s body, distal constricted portion and distal pore. Pair of cirri E (46 μm) each with proximal portion and flagellum arise from between postero-lateral and caudal alarum caesti. Rosette-like female gonopore opens 27 μm anterior to anus. Pair of seminal receptacles sited laterally at a level between gonopore and anus. Seminal receptacle consists of sinuous duct, which opens 29 μm laterally from gonopore and terminates in spherical vesicle 9 μm in diameter. Each leg terminates in four digits with proximal wrinkles and distal claws. External digits with hook-shaped peduncle. Internal digits longer than external digits. Internal claws with dorsal spur. External claws with calcar and avicularia. Internal claws smaller than external claws.

Etymology.

The specific epithet, wunai, is a Ryukyuan word for “sister” ( Nakamoto 1981) referring to the new species as a sister of Florarctus antillensis Van der Land, 1968, a species with similar morphology.

Remarks on paratypes.

The adult male, KUZ Z707, was smaller than adult females, KUZ Z705 and Z706, but had longer primary clavae relative to its body length (Table 2). The male gonopore of KUZ Z707 opens 10 μm anterior to the anus. The precise shape of male gonopore was not visible but spermatozoa were present inside the body. Excluding the lack of the genital structure, the paratypic four-clawed juvenile, KUZ Z709, was identical to the adults. A pair of bacterial vesicles is present in the paratypic four-clawed juvenile (Fig. 3C). For antero-lateral and postero-lateral alae, the number of slight indentations varied among specimens. There are two projections at the level of leg II in the paratypic specimen, KUZ Z708. The pair of small projections of the caudal alae caestus was better observed in the paratypes (Fig. 3D).

Differential diagnosis.

The presence of the continuous caestus and the absence of dorsal mammilla-like ornamentation, are shared by Florarctus antillensis , Florarctus glareolus Noda, 1987, Florarctus pulcher De Zio Grimaldi, Lamarca, D’addabbo Gallo & Pietanza, 1999 and Florarctus wunai sp. n. The new species is distinguished from these three species by the two small projections of the caudal alae caestus, which are long projections in Florarctus glareolus , long projections with swollen tips in Florarctus pulcher and absent in Florarctus antillensis (using Renaud-Mornant [1970] for information on the caestus morphology of Florarctus antillensis ).