Allobathynella imjinensis, Park & Cho, 2016

Park, Jong-Geun & Cho, Joo-Lae, 2016, Fourteen new species of Allobathynella Morimoto and Miura, 1957 from South Korea: with a redescription of A. coreana Morimoto, 1970 (Crustacea, Bathynellacea, Parabathynellidae), Journal of Species Research 5 (1), pp. 49-156 : 57-64

Allobathynella imjinensis sp. nov. ( Figs. 7-12 )

Etymology

The species name is derived from the river (Imjin), where the material was collected.

Material examined

Holotype (adult male), allotype (adult female), paratypes (five adult males and ten adult females). Holotype: dissected on seven slides ( NIBR IV0000266795 ) . Allotype: dissected on six slides ( NIBR IV0000266796 ) . Paratype: one adult male dissected on seven slides ( NIBR IV0000266797 ) , two adult females each dissected on six slides ( NIBR IV0000266798 , 000266799 ) , four adult males ( NIBR IV0000266800-0000266803 ) and eight adult females each as a total specimen on separate slides ( NIBR IV0000266804-0000266811 ) .

Type locality

South-Korea, Geonggi-Do, Yeoncheon-Gun Baekhak- Myeon Nogok-Ri (37°59′03.2″N, 126°55′45.9″E), 07. March 2009, leg. J.-L. Cho.

Description

Size (mm). Body length: ♂ 1.75 (other males: 1.74, 1.73, 1.73, 1.72), Ş 1.75, approximately 10 times as long as wide. Head slightly shorter than anterior three thoracic segments combined. Female differs from male in protopod of thoracopod VI, basipod of thoracopod VII and thoracopod VIII .

Antennule ( Fig. 7A ) 7-segmented. First segment with one seta on inner distal margin, with two simple dorsal setae and with four plumose setae. Position of each plumose setae: dorsally, dorso-laterally, laterally and ventro-laterally. Second segment with one group of four plumose setae and with each two simple setae dorsally and ventrally on inner distal margin, respectively. Third segment with two lateral setae including one plumose seta, with one ventrolateral seta, and two dorsal setae and two ventral setae on inner distal margin. Inner flagellum of third segment with three simple setae. Fourth segment with one stub setae and one plumose seta on dorsal margin, and with two stub setae and two plumose setae on outer distal apophysis. Fifth segment distally with two simple setae and one small plumose seta, two dorsal aesthetascs and one simple seta and medially with one simple seta on inner margin. Sixth segment with four setae including one plumose seta on inner margin, and with two aesthetascs and one simple seta and one aesthetasc dorsally. Seventh segment with three subterminal aesthetascs and four simple setae.

Antenna ( Fig. 7B ) 7-segmented, as long as length of antennular segments 1-5. Setal formula: 0 + 0/0 + 0/1 + 1/1 + 1/0 + 0/1 + 1 + 1/5(1). Outer seta of third segment tiny.

Labrum ( Fig. 7C ) flat, with eight main teeth flanked by three teeth on both lateral sides. Ventral surface concave, with one tiny round median projections without spinules beneath free margin, three pairs of teat and numerous combs of ctenidia.

Mandible ( Fig. 7D ) with incisor process of four teeth. Tooth of ventral edge absent. Spine row consisting of eight spines. Palp of one segment, 2.5 times as long as wide, with two apical setae of different size.

Maxillule ( Fig. 8A) two-segmented. Proximal segment with four setae on inner distal margin and with one setule. Distal segment with two terminal smooth spines and five dentate spines on inner edge, and with three simple setae on outer distal margin. Terminal spine two times larger than other ones.

Maxilla ( Fig. 8B) four-segmented, setal formula 3-4- 10-6.

Thoracopods I-VII ( Figs. 8 C-E, 9A, B, 10A, B, 11A, B). Thoracopod I-IV increasing in size posteriorly. Thoracopods IV-VII similar in size. Thoracopods III-VII each bearing one epipod on protopod. Basipod with two distal setae in thoracopod I, with one distal seta in thoracopods II-VI, and with each one distal and median seta in thoracopod VII. In female, basipod with each one distal and median seta in thoracopod VI, and with one distal seta and two median setae in thoracopod VII. Number of segments of exopod of thoracopods I-VII: 3-4-5- 5-5-5-5. Exopodal segments with each one dorsal and ventral seta, except basal segment lacking dorsal seta in thoracopods II-VII and second segment lacking dorsal seta in thoracopods VI and VII of female. Tiny process

February 2016 PARK AND CHO-FOURTEEN SPECIES OF ALLOBATHYNELLA 59

C A E C-E B D A, B

present between two setae of distal segment. Dorsal seta on distal segment of exopod barbed with strong hairs. Endopod of thoracopods I-VII four-segmented, setal formulae:

Thoracopod I 1 + 1/3 + 2/0 + 1/4(2)

Thoracopods II-V 1 + 1/2 + 2/0 + 1/4(2) Thoracopod VI 1 + 1/2 + 2/0 + 1/3(1) Thoracopod VII 0 + 1/1 + 2/0 + 1/3(1) Thoracopod VIII ( Fig. 11C, D ) of male perpendicular to body, in form of a bell in lateral view, 1.5 times longer than wide. Protopod with a prominent penial region bearing a distal opening. Inner margin of penial region (dental lobe) with ten or eleven teeth. Epipod flat, with flat round distal part not reaching lower margin of exopod. Basipod with one short seta near base of endopod, inner margin of basipod serrated, distally drawn out into round projection, basipodal seta one third as long as endopod. Exopod one third of size of basipod, round, with two distal lobes. Upper lobe with three spinules. Endopod small, round, with two distal setae of different size. Outer seta 1.5 times longer than inner one. Thoracopod VIII ( Fig. 10D ) of female tiny, round in ventral view, with two or three sharp projection distally.

First pleopod ( Fig. 10D ) in form of stub bearing two distal setae.

Uropod ( Fig. 12A, B ) bearing eight spines of similar size on inner margin of sympod. Endopod 47% as long as sympod, with two dorsal plumose setae near base, with two terminal setae and one subterminal plumose seta on outer margin and with one terminal spine, one subterminal spine and three additional spines along inner margin. Terminal spine slightly thicker and stronger than subterminal one. Spines of inner margin similar in size, half as large as terminal spine. Exopod slightly shorter than endopod (52% of sympod), with five setae inclusive of one basi-ventral seta.

Pleotelson ( Fig. 12B, C ) without seta. Anal operculum protruded slightly.

Furcal rami ( Fig. 12B, C ) nearly as long as wide, with two large distal spines, and three (left) or four (right) smaller spines on inner margin, and with two dorsal plumose setae.

Figures

Fig. 7. Allobathynella imjinensis (holotype: ♂). (A) Antennule (dorsal); (B) Antenna (dorsal); (C) Labrum (ventral); (D) Mandible (dorsal). Scale bars=0.05mm.

Fig. 11. Allobathynella imjinensis (holotype: ♂). (A) Thoracopod VII ♂(frontal); (B) Thoracopod VII Ş(frontal); (C) Thoracopod VIII ♂(lateral); (D) Left and right thoracopods VIII ♂(ventral). Scale bars=0.05mm.

Fig. 10. Allobathynella imjinensis (holotype: ♂; Allotype:Ş). (A) Thoracopod VI ♂ (frontal); (B) Thoracopod VI Ş(frontal); (C) Eight thoracomere and first pleomere Ş(ventral); (D) Thoracopod VIII Ş (ventral). Scale bars=0.05 mm.

Fig. 12. Allobathynella imjinensis (holotype: ♂). (A) Uropod (dorsal); (B) Uropod, pleotelson and furcal rami(lateral); (C) Pleotelson and furcal rami(dorsal); (D) Furcal ramus without spines(ventral). Scale bars=0.05 mm.