Allobathynella maseongensis, 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 : 64-69

Allobathynella maseongensis sp. nov. ( Figs. 13-18)

Etymology

The species name is derived from the Maseong-Myeon, where the material was collected.

Material examined

Holotype (adult male) dissected on eight slides ( NIBR IV0000266838 ).

Type locality

South-Korea, Kyungsangbuk-Do, Munkyeong-Si, Maseong-Myeon, Shinheon-Ri (36°39′39.1″N, 128°07′ 15.0″E), 13. October 2012, leg. J.-L. Cho.

Description

Size (mm). Body length: 2.55, approximately 12 times as long as wide. Head slightly shorter than anterior three thoracic segments combined ( Fig. 13A).

Antennule ( Fig. 13B) 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 three 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. 13C) 7-segmented, as long as length of antennular segments 1-5. Setal formula: 0+ 0/0 + 0/1 + 0/1 + 1/0 + 0/1 + 1 + 1/5(1).

Labrum ( Fig. 13D) flat, with eight main teeth flanked by seven (right) or six (left) 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. 13E) with incisor process of four teeth. Tooth of ventral edge absent. Spine row consisting of ten spines. Palp of one segment, 2.5 times as long as wide, with two apical setae of different length.

Maxillule ( Fig. 14A) two-segmented. Proximal segment with numerous numbers of ctenidia and with four setae on inner distal margin. 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 1.5 times larger than other ones.

Maxilla ( Fig. 14B) four-segmented, setal formula 4-5- 12-6.

Thoracopods I-VII ( Figs. 14 C-E, 15A, B, 16A, B). Thoracopod I-IV increasing in size posteriorly. Thoracopods IV-VII similar in size. Thoracopods VI-VII each bearing one epipod on protopod. Basipod with two distal setae in thoracopod I, with one distal seta in thoracopods II, III, and with each one distal and median seta in thoracopods IV-VII. Number of segments of exopod of thoracopods I-VII: 3-4-6-6-6-6-6. Exopodal segments with each one dorsal and ventral seta, except basal segment lacking dorsal seta in thoracopods III. Tiny process 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 2 + 1/4 + 2/2 + 1/4(2)

Thoracopod II 2 + 1/3 + 2/1 + 1/4(2)

Thoracopod III 1 + 1/2 + 2/1 + 1/4(2)

Thoracopods VI-VI 1 + 1/2 + 2/0 + 1/4(2)

Thoracopod VII 0 + 1/1 + 1/0 + 1/4(2)

Thoracopod VIII ( Fig. 17 A-C) of male perpendicular to body, in form of a bell in lateral view, 1.3 times longer than wide. Protopod with a prominent penial region bearing a distal opening. Inner margin of penial region (dental lobe) with seven teeth. Epipod flat, anteriorly protruded, distal part mostly not, but anterior protrusion reaching bottom of exopod. Basipod with one seta near base of endopod, inner margin of basipod with numerous rows of fine setules, distally drawn out into round projection, basipodal seta as long as endopod. Exopod one third of size of basipod, round, with two distal lobes. Upper lobe with three teeth. Endopod small, round, with two distal setae of different size. Inner seta extremely short, as long as basipodal seta.

First pleopod ( Fig. 16C ) in form of stub bearing two distal setae.

Uropod ( Fig. 18A, B ) bearing 12 spines on inner margin of sympod, two most distal spines somewhat longer

February 2016 PARK AND CHO-FOURTEEN SPECIES OF ALLOBATHYNELLA 65 66 JOURNAL OF SPECIES RESEARCH Vol. 5, No. 1 February 2016 PARK AND CHO-FOURTEEN SPECIES OF ALLOBATHYNELLA 69

A B, C B C A 1.0 mm D E D, E

B A E C D A, B D, E

B epipod A exopod endopod basipod C

than others. Endopod 52% 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 four additional spines along inner margin. Terminal spine slightly longer than subterminal one. Most distal spine of inner margin two thirds as large as terminal spine and 4-5 times larger than proximal three ones of similar size. Exopod slightly shorter than endopod (49% of sympod), with six setae inclusive of one basi-ventral seta.

Pleotelson ( Fig. 18B, C ) without seta. Anal operculum round and protruded slightly.

Furcal rami ( Fig. 18B, C ) 1.2 times as long as wide, with two large distal spines, and five successively small- er spines on inner margin, and with two dorsal plumose setae.

Figures

Fig. 16. Allobathynella maseongensis (holotype: ♂): (A) Thoracopod VI (frontal); (B) Thoracopod VII (frontal); (C) Pleopod (ventral). Scale bars=0.1 mm.

Fig. 18. Allobathynella maseongensis (holotype: ♂): (A) Uropod (dorsal); (B) Pleotelson and furcal rami (dorsal); (C) Uropod, pleotelson and furcal rami(lateral). Scale bars=0.1 mm.