Bairdoppilata japonica, Horikoshi & Nakao & Tsukagoshi, 2019

Horikoshi, Hideyuki, Nakao, Yuriko & Tsukagoshi, Akira, 2019, Two new species of Bairdiidae (Ostracoda: Crustacea) from the western Pacific coast of Japan, Zootaxa 4679 (3), pp. 450-462 : 457-461

publication ID	https://doi.org/ 10.11646/zootaxa.4679.3.2
publication LSID	lsid:zoobank.org:pub:13EF227C-33FF-4E10-B863-FA2623F36198
persistent identifier	https://treatment.plazi.org/id/03CC9E2F-FF85-DC07-C8C9-4EA9FE61C974
treatment provided by	Plazi
scientific name	Bairdoppilata japonica
status	sp. nov.

Treatment

Bairdoppilata japonica View in CoL sp. nov.

( Figs. 4C, D View FIGURE 4 , 6B View FIGURE 6 , 7 View FIGURE 7 , 8 View FIGURE 8 , 9 View FIGURE 9 )

Type series. All examined specimens collected at tidal pool of rocky shore, in Shionomisaki, Wakayama Prefecture, western Honshu, Japan (33° 25′ 59″ N, 135° 45′ 45″ E; Fig. 1 View FIGURE 1 ) on 29th August 2008 GoogleMaps . Holotype: adult male ( SUM- CO- 2456), right valve length 0.92 mm, height 0.52 mm, left valve length 0.93 mm, height 0.57mm, appendages mounted on slide and valves preserved in cardboard cell slide . Paratypes: 2 adult males ( SUM CO- 2457 and 2458) and 2 adult females (SUM-CO-2459, 2460).

Etymology. Named after first record of this genus from Japan.

Diagnosis. Male copulatory organ with distal lobe divided toward dorsally, elongated Y-shaped apparatus deriving from center of basal capsule to outside, and coiled copulatory duct.

Description. Carapace ( Figs. 4C, D View FIGURE 4 , 7 View FIGURE 7 , 8 View FIGURE 8 ) streamlined sub-hexagonal in lateral view. Surface covered with numerous fine pits and simple type pore-systems. Left valve larger than right valve and overlapping along dorsal and ventral margins. Posterior margin of right valve finely serrated and strongly serrated in left valve ( Fig. 7 View FIGURE 7 C‒F). Several feathered setae of pore systems concentrating at posterior end in both valves. Central muscle scars consisting of 8 adductor scars, 2 mandibular scars, 2 frontal scars and 3 limb scars, including 1 fulcral point ( Fig. 8E, F View FIGURE 8 ). Hingement weak and simple: right valve bearing simple elongated bars as anterior and posterior elements and narrow dorsal groove ( Fig. 8A View FIGURE 8 ); left valve bearing incised groove with dorsal awning and ventro-terminal small triangular sockets ( Fig. 8B View FIGURE 8 ). Distinct auxiliary dentition at upper internal sides of anterior and posterior ends of both valves ( Fig. 8A, B View FIGURE 8 ).

Antennule ( Fig. 9A View FIGURE 9 ). Seven articulated podomeres, length ratio among them from proximal to distal 21: 14: 4: 4: 2: 3: 1. Three terminal podomeres with much longer setae than total length of antennule. First podomere with assemblage of setulae at antero-distal corner. Second podomere with 1 long apical seta at postero-distal corner. Third podomere with 1 medium-long apical seta at postero-distal corner. Fourth podomere with 1 very short and 1 short apical setae at anterior and posterior distal corners, respectively. Fifth podomere with 2 very long setae on both anterior and posterior distal ends, respectively. Sixth podomere with 2 and 3 very long setae on anterior and posterior distal ends, respectively. Seventh (terminal) podomere with 5 very long setae grouped together at bases on distal end.

Antenna ( Fig. 9B View FIGURE 9 ). Five articulated podomeres, length ratio among them from proximal to distal 4: 2: 3: 5: 1. First podomere (protopodite): Indistinctly fused between coxa and basis, with 2 medium-long setae in posterior proximal area, 1 long seta at postero-distal end and 1 long seta at antero-distal end. Second podomere with 3 setae of equal medium-length on middle of ventral margin, 2 medium-long apical setae at posterior distal corner and 1 long seta on proximal area. Third podomere with 1 long stout setulous apical seta at posterior distal corner, 1 very short seta on distal end. Fourth podomere with 1 short seta on ledge at one-fifth from anterior proximal end, 2 short setae on ledge at four-fifths from anterior proximal end, 1 short claw-like seta on posterior distal margin. Numerous setulae along distal half of posterior margin. Fifth (terminal) podomere with 3 stout terminal claws and 1 short seta.

Mandibula ( Fig. 9C View FIGURE 9 ). Consisting of 5 podomeres, length ratio among them from proximal to distal 8: 3: 1: 2: 1. First podomere (coxa) with masticatory part of 4 stout trilobed denticles and several fine setae on distal end. One short simple seta (endite) on anterior dorsal margin. First podomere of palp (basis) with 1 seta on antero-distal corner and middle of distal end, respectively, and branchial plate (reduced exopodite) consisting of 1 very long and 2 long, plumose setae on dorso-proximal end. Second podomere of palp (1st podomere of endopodite) with 2 medium setae on middle of antero margin, 1 medium apical seta at posterior distal corner, and 2 medium setae on posterior distal margin. Third podomere of palp (2nd podomere of endopodite) with 3 simple seta on ledge of anterior margin, 2 short and 1 short, stout setae on posterior distal end. Fourth (final) podomere with 1 simple seta on middle of anterior margin, 1 stout distal claw, and 3 setae of unequal lengths on posteror-distal end.

Maxillula ( Fig. 9D View FIGURE 9 1 View FIGURE 1 , D 2 View FIGURE 2 ). Thin branchial plate (exopodite) bearing 23 plumose setae and 6 long, reflexed setae. Basal podomere bearing 1 palp and 3 masticatory endites. Palp with 1 and 3 medium setae on ventral and dorsal ledges, respectively, 1 stout serrated claw, and 1 medium seta on distal end. First (ventral-most) endite with 1 short seta on ventral margin at four-fifths from proximal end, 3 short, stout and 4 short, thin setae on distal end. Second endite with 1 small spatula-like seta, 1 short serrated claw, 3 short setae on distal end. Third endite with 2 short, stout, serrated claws, 1 short seta on distal end.

Brush-shaped organ (in male) ( Fig. 9F View FIGURE 9 ). Consisting of paired branches. Well-developed right branch approximately 3 times length of left one and bearing more than 20 long, thin setae on distal end. Left branch with less than 20 medium-long setae.

Fifth limb ( Fig. 9F View FIGURE 9 ) Consisting of 5 articulated podomeres, length ratio among them from proximal to distal 11: 7: 4: 5: 1. First podomere with branchial plate (bearing 13 plumose setae on middle of ventral margin and 4 smooth setae of equal length grouped proximally) 1 seta on anterior margin at two-thirds from proximal end, 3 setae on ledge on anterior margin at three-fourths from proximal end, and 2 long and 2 medium setae on distal end. Second podomere with 1 long, stout and 1 medium apical setae at anterior distal corner. Third podomere with 1 short, stout seta at anterior distal corner. Fourth podomere with 1 very short, stout seta at anterior distal corner. Fifth podomere with 1 fine seta and 1 medium-long terminal claw on distal end.

Sixth limb ( Fig. 9G View FIGURE 9 ). Consisting of 5 articulated podomeres, length ratio among them from proximal to distal 9: 7: 4: 7: 1. First podomere with 1 medium and 1 long seta on anterior margin at one-third and two-thirds from proximal end, respectively, 2 medium setae on posterior margin of three-fourths from proximal end, and 2 medium setae on anterior-distal end. Second podomere with 2 setae of different length on anterior-dorsal end. Third podomere with 1 stout, short apical seta at anterior-distal corer. Fourth podomere with 1 short, stout apical seta at antero-distal corner. Fifth podomere with 1 very short seta on antero-distal end and 1 long, curved terminal claw on distal end.

Seventh limb ( Fig. 9H View FIGURE 9 ). Consisting of 5 articulated podomeres, length ratio among them from proximal to distal 8: 6: 4: 7: 1. First podomere with 1 seta each on anterior margin at one-half and three-fourths from proximal end, respectively, 2 medium setae on middle of posterior margin, 1 seta each at antero-distal corner and on distal end, respectively. Second podomere with 1 medium and 1 short setae at anterio-distal corner. Third podomere with 1 short, stout seta at anterio-distal corner. Fourth podomere with 1 short seta at anterio-distal corner. Fifth podomere with 1 very short seta at anterio-distal corner, and 1 long, curved terminal claw on distal end.

Furca ( Fig. 6B View FIGURE 6 ). Bearing 7 setae. Terminal 2nd most seta (2) twice as long as terminal most seta (1). Proximal most and 2nd most setae (6 and 7) almost as long as terminal 3rd most seta (3).

Caudal process ( Fig. 6B View FIGURE 6 ). One simple short seta.

Male copulatory organ ( Fig. 6B View FIGURE 6 ). Massive oval basal capsule. Distal lobe rounded in outside and two-divided in inside. Elongated Y-shaped apparatus developing from center to outside. Copulatory duct coiled.

Eye. Naupliar eyes present without clear cuticular lens.

Dimensions. See Table 2.

Remarks. This new species resembles Bairdoppilata villosa ( Brady, 1880) in the carapace outline and most features of the appendages. However, this new species is different from B. villosa in the morphology of the male copulatory organ; the copulatory duct is longer and coiled. The distal lobe is large and divided on the internal side in B. japonica sp. nov.