Two four-clawed juveniles found in sediment sample 4 (Table 1).

The species resembles Dipodarctus borrori Pollock, 1995 and D. susannae Jørgensen, Boesgaard, Møbjerg & Kristensen, 2014 by having digits of unequal length on legs I–III and the lack of lateral processes between legs III and IV. It is distinguished from the two species by the lateral cirrus lack of scapus, which is present in the both D. borrori and D. susannae. It is also distinguished from D. borrori by the shorter digit 1 of legs I–III and from D. susannae by its shorter papillate leg IV sense organ. These observations are based on comparing juveniles with descriptions of adults so while this species is probably an undescribed species observation of an adult specimen is required for confirmation.

Figure 1. 

Phase contrast micrograph of Dipodarctus sp. Scale bar = 20 μm.

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.

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).

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.

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

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.

Figure 2. 

Drawing of Florarctus wunai sp. n., holotype KUZ Z705. A dorsal view B ventral view of cephalic region. a anus; AL anterolateral ala; C caudal ala; ca caestus; cE cirrus E; ec external cirrus; F frontal ala; g gonopore; ic internal cirrus; lc lateral cirrus; mc median cirrus; mo mouth; pb pharyngeal bulb; pc primary clava; PL postero-lateral ala; sc secondary clava; sr seminal receptacle; s1–4 leg I–IV sense organs.

Figure 3. 

Phase contrast micrograph of Florarctus wunai sp. n. A dorsal view, holotype KUZ Z705, scale bar = 100 μm B secondary clavae (white arrowhead), holotype KUZ Z705, scale bar = 20 μm C bacterial vesicles (white, hollow arrowhead), paratype KUZ Z709, scale bar = 20 μm D caudal alae caestus with pair of small projections (black arrowhead), paratype KUZ Z708, scale bar = 20 μm.

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.

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).

The presence of the continuous caestus and the absence of dorsal mammilla-like ornamentation, are shared by Florarctus antillensis, F. glareolus Noda, 1987, F. pulcher De Zio Grimaldi, Lamarca, D’addabbo Gallo & Pietanza, 1999 and F. 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 F. glareolus, long projections with swollen tips in F. pulcher and absent in F. antillensis (using Renaud-Mornant [1970] for information on the caestus morphology of F. antillensis).

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.

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

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

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.

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

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.

Figure 4. 

Drawing of Halechiniscus churakaagii sp. n., holotype KUZ Z710 (dorsal view). a anus; cE cirrus E; d seminal receptacle duct; ec external cirrus; g gonopore; ic internal cirrus; lc lateral cirrus; mc median cirrus; mo mouth; pb pharyngeal bulb; pc primary clava; sc scapular process; s1–4 leg I–IV sense organs.

Figure 5. 

Phase contrast micrograph of Halechiniscus churakaagii sp. n., holotype KUZ Z710. A dorsal view, scale bar = 50 μm B ventral view, scale bar = 50 μm C scapular process (white arrowhead), scale bar = 10 μm D cirrus E with dark region (white, hollow arrowhead), scale bar = 20 μm.

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

The robust cirrophores of the median and lateral cirri are present in Halechiniscus chafarinensis De Zio Grimaldi & Villora Moreno, 1995, H. macrocephalus Grimaldi de Zio, D’Addabbo Gallo & Morone De Lucia, 1988, H. paratuleari Grimaldi de Zio, D’Addabbo Gallo & Morone De Lucia, 1988, H. tuleari Renaud-Mornant, 1979 and H. churakaagii sp. n. Among these species, H. paratuleari and the new species are the only species with large scapular processes. The new species is distinguished from H. 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 H. tuleari and H. paratuleari.

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.

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

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.

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

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.

Figure 6. 

Drawing of Halechiniscus yanakaagii sp. n., holotype KUZ Z712 (dorso-lateral view). cE cirrus E; dp1–2 anterior and posterior double processes; ec external cirrus; g gonopore; ic internal cirrus; lc lateral cirrus; mc median cirrus; mo mouth; pb pharyngeal bulb; pc primary clava; s1–4 leg I–IV sense organs.

Figure 7. 

Phase contrast micrograph of Halechiniscus yanakaagii sp. n., holotype KUZ Z712. A dorso-lateral view, scale bar = 50 μm B double processes (white arrowhead), scale bar = 10 μm.

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

Halechiniscus yanakaagii sp. n. and H. tuleari are the only two Halechiniscus species with double processes at the level of leg I. The new species is distinguished from H. 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 H. tuleari.

One female adult and one four-clawed juvenile found in sediment sample 4 (Table 1).

The individuals found resemble Styraconyx nanoqsunguak Kristensen & Higgins, 1984 by the dorsal ridges (Fig. 8A, B). However, these specimens are distinguished by the lateral cirrus with no scapus (which is present S. nanoqsunguak), longer peduncles of the external digits and leg IV sense organs consisting of a spherical papilla and a distal spine (which is an elongate papilla and a shorter distal spine in S. nanoqsunguak). While I believe this is a new undescribed species, lack of visible taxonomic characters has hindered providing a complete species description.

Figure 8. 

Phase contrast micrograph of Styraconyx sp. A ventral view, scale bar = 50 μm B dorsal cuticle with ridges, scale bar = 20 μm.