Brevisomabathynella cunyuensis, Cho, Joo-Lae, Park, Jong-Geun & Reddy, Y. Ranga, 2006

Cho, Joo-Lae, Park, Jong-Geun & Reddy, Y. Ranga, 2006, Brevisomabathynella gen. nov. with two new species from Western Australia (Bathynellacea, Syncarida): the first definitive evidence of predation in Parabathynellidae, Zootaxa 1247, pp. 25-42 : 33-38

Brevisomabathynella cunyuensis sp. nov.

( Figures 5–9 )

Etymology

The specific epithet refers to Cunyu Station.

Type material

Holotype: female, dissected on seven slides. Australia, Western Australia, Cunyu Station, site 289. Exploration Bore along State Barrier fence (25°46’51”S, 120°06’27”E), BES 8120, 5 November 2001 (W.F. Humphreys, T. Karanovic and J.M. Waldock) ( WAM C 36706). Allotype: male, dissected on seven slides, same data as holotype ( WAM C 36707). Paratypes: 2 males and 4 females, each as a whole specimen on a slide, same data as of holotype ( WAM C 36708 ­ 36713).

Description of female (holotype)

Body thick, length 1.72 mm (other females: 1.65–1.80 mm), approximately 4.5 times as long as wide. Head as long as anterior thoracic segments 1–5 combined.

Antennule ( Fig. 5 B) seven­segmented, setation as in B. cooperi except for four simple setae occurring on inner distal margin of second segment and third segment with three setae on inner distal margin.

Antenna ( Fig. 5 C) five­segmented, as long as antennular segments 1–4 combined. Setal formula: 0+0/0+0/1+1/1+1/3(1). Plumose seta of the fifth segment as long as terminal simple seta.

Labrum ( Fig. 5 D) flat and huge, circular in ventral view, and with 53 narrow teeth of more or less similar size, flanked by five teeth, gradually decreasing in size on both sides. Inner surface with four pairs of teats and numerous combs of ctenidia.

Mandible ( Figs 5 E, 5F) with incisor process of seven teeth. Tooth of ventral edge triangular. Spine row consisting of eight spines bearing numerous denticles. The most proximal spine with one seta at its base. A tiny opening discernible near the most distal spine. Palp of one segment, with one apical seta, not reaching beyond pars incisiva.

Maxillule ( Fig. 5 G) two­segmented. Armature as in B. cooperi except for the most ventral seta on disto­outer margin of the distal segment being short, barely reaching base of terminal claw.

Maxilla ( Fig. 5 H) four­segmented, setal formula: 4­4­8­6.

Thoracopods I–IV ( Figs 7 A, B, C, D) increasing in length posteriorly. Thoracopods IV –VI ( Figs 7 D, 8A, B) almost similar in length. Thoracopod VII ( Fig. 8 C) only slightly longer than thoracopod I. Exopod longer than endopod on thoracopods II–VI; both rami almost equal in length on thoracopods I and VII. Thoracopods I–VII each bearing one epipod on protopod, and one inner seta on basipod. Number of exopodal segments of thoracopods I–VII: 5­6­7­7­7­6­5. Endopod of thoracopods I–VII 4 ­segmented, setal formulae:

Thoracopod I 3 +1/3+1/1+1/3(1)

Thoracopod II 1 +1/2+1/0+1/3(1)

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

Thoracopod IV, V 1 +1/2+1/0+1/3(1)

Thoracopod VI 1 +1/2+1/0+1/2(0)

Thoracopods VII 1 +1/1+1/0+1/2(0)

Thoracopod VIII ( Fig. 6 A) as in B. cooperi .

First pleopod ( Fig. 6 A) stalk­like, bearing two setae.

Uropod ( Figs 6 G, H): sympod about five times as long as wide, bearing ten spines of similar size on inner margin. Endopod half as long as sympod, with two dorsal plumose setae near base, two terminal setae, one subterminal plumose seta on outer margin, and six spines on inner margin, distal two spines larger than others. Exopod slightly longer than endopod, with two terminal and five outer marginal setae.

Pleotelson ( Fig. 6 F, H) with one short seta on either side at base of furcal ramus. Anal operculum concave.

Furcal rami ( Fig. 6 F, I) twice as long as wide, with two large distal spines, and eight or nine smaller spines on inner margin, and with two dorsal setae.

Description of male

The male differs from the female in the body length and the thoracopod VIII. Body ( Fig. 5 A) length 1.15 mm (other males: 1.15, 1.08 mm).

Thoracopod VIII ( Figs 6 B, C, D, E) more or less rectangular in lateral view, 1.5 times longer than wide. Protopod massive, with prominent penial region with a distal opening. Inner margin of the distal opening with tiny denticles. Epipod large, triangular, its distal part reaching distal opening of penial region. Basipod without setae, inner margin of basipod drawn out into hook­like projection. Exopod one­third the size of basipod, triangular, bearing two subterminal setae, serrated distally. Endopod as large as exopod, with two distal setae.

Figures

FIGURE 5. Brevisomabathynella cunyuensis sp. nov., (Ψ: holotype, ɗ: allotype): A. habitus ɗ (lateral); B. left antennule Ψ (dorsal); C. left antenna Ψ (dorsal); D. labrum Ψ; E. left mandible Ψ (dorsal); F. molar process of left mandible Ψ (dorsal); G. right maxillule Ψ (dorsal); H. right maxilla Ψ (dorsal). Scale bars = 0.1 mm.

FIGURE 6. Brevisomabathynella cunyuensis sp. nov. (Ψ: holotype, ɗ: allotype): A. eigth thoracomere and first pleomere with thoracopods VIII Ψ and pleopods (ventral); B. right and left thoracopods VIII ɗ (frontal); C. right thoracopod VIII ɗ (rear view); D. basipod and endopod of left thoracopods VIII ɗ (frontal); E. exopod of the left thoracopods VIII ɗ (frontal); F. pleotelson and furcal rami Ψ (dorsal); G. left uropod Ψ (dorsal); H. pleotelson and furcal rami Ψ (lateral). Scale bars = 0.1 mm.

FIGURE 7. Brevisomabathynella cunyuensis sp. nov. (Ψ: holotype): A. left thoracopod I Ψ (frontal); B. left thoracopod II Ψ (frontal); C. right thoracopod III Ψ (frontal); D. left thoracopod IV Ψ (frontal). Scale bar = 0.1 mm.

FIGURE 8. Brevisomabathynella cunyuensis sp. nov. (Ψ: holotype): A. left thoracopod V Ψ (frontal); B. left thoracopod VI Ψ (frontal); C. left thoracopod VII Ψ (frontal). Scale bar = 0.1 mm.

FIGURE 9. Ostracod in the gut of Brevisomabathynella cunyuensis sp. nov.