Pseudocandona tenuirostris, Hiruta & Mawatari, 2013

Hiruta, Shimpei F. & Mawatari, Shunsuke F., 2013, Ostracods (Crustacea) from Sarobetsu Marsh, Northern Hokkaido, Japan: Taxonomy and Phenology with Description of Pseudocandona tenuirostris sp. nov., Species Diversity 18, pp. 57-74 : 59-67

publication ID	https://doi.org/ 10.12782/sd.18.1.057
publication LSID	lsid:zoobank.org:pub:CF9B52C8-3340-417A-BDEB-8DAB70B7A99E
persistent identifier	https://treatment.plazi.org/id/C8B0ED9E-B1B2-4ABB-B284-183AF7369E3C
taxon LSID	lsid:zoobank.org:act:C8B0ED9E-B1B2-4ABB-B284-183AF7369E3C
treatment provided by	Felipe
scientific name	Pseudocandona tenuirostris
status	sp. nov.

Treatment

Pseudocandona tenuirostris sp. nov.

( Figs 7–11 View Fig View Fig View Fig View Fig View Fig )

Type material. Holotype: ZIHU 3916 View Materials , male, site C ( Table 1), Sarobetsu Marsh , Rishiri Rebun Sarobetsu National Park, Hokkaido, Japan ( Fig. 1 View Fig ), 28 May 2005, soft parts mounted on 20 slides, carapace mounted on a microfossil slide . Allotype: ZIHU 3917 View Materials , female, same site, Sarobetsu Marsh, 10 May 2005, soft parts mounted on 15 slides, carapaces mounted on a microfossil slide . Paratypes: ZIHU 3918, 3919, two males, same data as for allotype, mounted on slides; ZIHU 3920, 3921, two females, same data as for allotype, mounted on slides; ZIHU 3922, 3923, two males, same data as for allotype, mounted on stubs for SEM observation.

Description of male. Carapace ( Figs 7A, B, D View Fig , 8A–C View Fig ) 1.24–1.27 mm long, 0.71–0.74 mm high (n =4; 1.25 mm long, 0.71 mm high in holotype); moderately compressed in dorsal view, posterior end round, anterior end slightly beak shaped ( Fig. 8C View Fig ); left valve overlapping right valve both anteriorly and posteriorly. Dorsal margin straight in lateral view, sloping towards anterior end; greatest height exceeds half the length. Surface of valves with long, stiff, perpendicularly attached setae and covered with numerous tiny pits observable by SEM ( Fig. 7A, B View Fig ).

Antennule ( Fig. 8D View Fig ) seven-segmented. First two podomeres fused, with two long dorsal setae and two long apicoventral setae. Third podomere quadrate, with apico-dorsal seta. Fourth podomere quadrate, with apico-dorsal seta. Fifth and sixth podomeres both quadrate, each with two long apico-dorsal setae. Seventh podomere with two long and one shorter apico-dorsal setae. Eighth podomere elongate and slender, with two long setae, one shorter seta, and aesthetasc ya.

Antenna ( Fig. 8E View Fig ) five-segmented. First podomere with one long, apico-ventral seta, one medium-long, anteroproximal, plumose seta, one long, antero-proximal seta, and one long latero-proximal seta. Second podomere with two apico-ventral setae, aesthetasc Y, and exopodite (Exo); exopodite consisting of one long and two short setae. Third podomere with two mid-apical male bristles (t2 and t3), one short apico-ventral and one apico-dorsal setae, and short mid-ventral seta. Fourth podomere with long G 1 and G 3, short G 2, and three apico-ventral setae. Fifth podomere with GM and shorter Gm, one apical seta, and aesthetasc y 3.

Mandible ( Fig. 9A View Fig ) consisting of coxal plate and four-segmented palp. Coxal plate with antero-lateral plumose seta and seven stout teeth, latter interspersed with several setae of various lengths. First podomere of palp with exopodal plate (Exo) and one long and one short inner-distal plumose setae, one long antero-distal seta, and alpha plumose seta. Second podomere of palp with beta seta and group of three setae. Third podomere of palp with three outer apical setae, one mid-apical gamma seta, and two medium-long and one short inner apical setae. Fourth podomere of palp with one distally plumed claw, two apical setae, and one shorter apical seta.

Maxillula ( Fig. 9B View Fig ) with elongate vibratory plate, three masticatory processes, and two-segmented palp. First podomere with two long, apical plumose setae.

Maxilliped ( Fig. 9C, D View Fig ) with palp, vibratory plate (Exo), one antero-proximal seta, one antero-apical seta, and one postero-apical seta. Vibratory plate with two filaments. Palp transformed into asymmetrical clasping organs; left clasping organ ( Fig. 10E View Fig ) slender, curved, with two short distal setae; right clasping organ ( Fig. 10F View Fig ) helmet-shaped, with two short distal setae. Masticatory process with numerous setae.

Walking leg ( Fig. 10A View Fig ) five-segmented. Terminal claw (h 2) long, with denticles covering about half the length.

Cleaning leg ( Fig. 10B View Fig ) five-segmented. Penultimate segment subdivided. First podomere with three setae. Fourth podomere with one apical seta. Fifth podomere with two long (h 2, h 3) and one shorter (h 1) setae.

Uropodal ramus ( Fig. 10C View Fig ) with anterior seta and welldeveloped posterior seta. Two terminal claws with tiny denticles.

Hemipenis ( Fig. 10D View Fig ) distally with three lobes. Medial lobe (h) longest among three, distally beak-shaped ( Fig. 7F View Fig ). Outer lobe (a) narrow, shortest, usually angling away somewhat obliquely ( Figs 7E View Fig , 10D View Fig ). Inner lobe (b) overlapping to medial lobe. Peniferum, inner lobe, and medial lobe, altogether tapering distally. M process (M) well developed, proximally branched for three parts. The brusa complex (e) pointed and forked at proximally.

Zenker’s organ ( Fig. 11 View Fig ) with 5+2 internal rings of spines.

Description of female. Carapace 1.15–1.20 mm long, 0.63–0.64 mm high (n =3; 1.17 mm long, 0.63 mm high in allotype). Carapace slightly shorter and posteriorly lower and narrower than that of male.

Antenna ( Fig. 8F View Fig ) four-segmented. First and second podomeres similar to those of male. Third podomere with long G 1 and G 3, shorter G 2, one long and one short apicodorsal setae, one apico-ventral aesthetasc y 2, and two midventral setae. Fourth podomere with GM, shorter Gm, one apical seta, and aesthetasc y 3.

Palp of Maxilliped ( Fig. 9E View Fig ) simple, non-segmented, with three apical setae.

The other parts of female similar to male.

Remarks. In having three setae in the setal group on the second segment of the mandibular palp ( Fig. 9A View Fig ), Pseudocandona tenuirostris sp. nov. belongs to the Ps. rostrata ( Brady and Norman, 1889) species group ( Meisch 1996). The soft parts of Ps. tenuirostris ( Fig. 7C View Fig ) are similar in the morphology to those of Ps. rostrata , but the shape of the carapace is similar to that of Ps. sarsi (Hartwig, 1899) (Hartwig 1899; Meisch 2000). There are clear differences in the clasping organs and the hemipenis between Ps. tenuirostris and the latter two species. In Ps. tenuirostris , both the left and right male clasping organs are relatively long and slender ( Fig. 10E, F View Fig ); the fingers of both organs are shorter than in Ps. rostrata and more slender than in Ps. sarsi . In all three species, the hemipenis comprises three distal lobes, but in Ps. tenuirostris the medial lobe (h) is longest, very narrow, and beak-shaped; the outer lobe (a) is shortest. In contrast, in Ps. rostrata , the medial lobe (h) is stout and longest, whereas the inner lobe (b) is shortest; in Ps. sarsi , the outer lobe (a) is well developed and longer than the stout medial lobe (h).

Etymology. The new specific name is an adjective, derived from the combination of the Latin tenuis meaning “thin” or “fine” and rostris meaning “of beak”, referring to the fine, beak-like medial lobe on the distal end of each hemipenis.