Bunakenia betatari, Bamber, Roger N., 2013

Bamber, Roger N., 2013, Tanaidaceans from Brunei, IV. The Families Kalliapseudidae, Pagurapseudopsidae, Parapseudidae and Apseudidae (Crustacea: Peracarida: Tanaidacea: Apseudomorpha), with descriptions of a new genus and six new species, Zootaxa 3734 (4), pp. 401-441 : 433-438

Genus Bunakenia Guţu 1995

Bunakenia betatari sp. nov. Figs 17–19

Material: 1♀ with oostegites, holotype (BMNH 2013.897), 1♂, 2♀♀ (one brooding), paratypes (BMNH 2013.898–901), 1♀ (dissected, retained), Station BU, 04°51′06"N 114°35′26"E, 20 m depth, sand; March 2009. 1♀, paratype (BMNH 2013.902), Station B12, 04°51′06"N 114°35′26"E, 20 m depth, sand; March 2009. 2♀♀, paratypes (BMNH 2013.903–904), Station DA2, 05°54′28.5"N 114°38′23.3"E, 20 m depth, sand.

Description of female: body ( Fig. 17 A) elongate, six times as long as wide, holotype 2.9 mm long. Cephalothorax with convex lateral margins, glabrous, as long as wide, about as long as pereonites 1 and 2 together, with triangular pointed rostrum; eyelobes present, eyes of about eight ommatidia, pigmented (brown in preserved material). Pereonites 1 and 2 naked, with convex lateral margins; pereonites 2 to 6 with lateral indentations at midlength but without apophyses, with single setae at anterolateral corners, pereonite 4 with additional anterolateral and posterolateral setae. Pereonite 1 shortest, about half as long as cephalothorax; pereonite 2 slightly longer than pereonite 1; pereonites 3, 5 and 6 subequal in length, 1.4 times as long as pereonite 1; pereonite 4 just shorter, 1.3 times as long as pereonite 1 (all pereonites respectively 2, 1.7, 1.4, 1.5, 1.3 and 1.2 times as wide as long). Pleonites about five times as wide as long, pleonites 4 and 5 longer and narrower than anterior pleonites; each pleonite with slightly extended, triangular epimera bearing lateral simple seta. Pleotelson subpentangular, twice as long as pleonite 5, about as long as wide, laterally with two marginal setae, distally with two longer dorsal setae and two mid-posterior setae as in Fig. 19 B.

Antennule ( Fig. 17 B) longer than cephalothorax, proximal peduncle article 3.8 times as long as wide without marginal tuberculation, inner margin with three subdistal and two mid-length simple setae, outer margin with one simple distal seta and three penicillate setae at mid-length; second article twice as long as wide, 0.4 times as long as first article, with inner and outer distal tufts of simple setae; third article half length of second, with paired inner and outer simple distal setae; distal peduncle article 0.7 times as long as third article, with one distal seta. Main flagellum of seven segments, single aesthetascs on segment 4; accessory flagellum of three segments.

Antenna ( Fig. 17 C) proximal peduncle article without apophysis, naked; second article 1.5 times as long as first, naked, squama a narrow oval bearing six marginal simple setae; third peduncle article short, half as long as first article, naked; fourth article as long as first article, with one inner simple seta; fifth article 1.6 times as long as fourth with three simple distal setae. Flagellum of five segments, mostly sparsely setose, but first flagellum segment with outer tuft of three simple setae.

Labrum ( Fig. 17 D) apically rounded, setose. Left mandible ( Fig. 17 E) with four rounded teeth on pars incisiva, lacinia mobilis elongate with two distal teeth, setiferous lobe bearing one simple and two bifurcate setae; pars molaris robust with wide, bilobed distal face; first article of mandibular palp bearing four distal and mesial simple setae, second article with two ventral setae, third article with three distal setae. Right mandible ( Fig. 17 F) similar to left mandible but without lacinia mobilis, setiferous lobe bearing three bifurcate setae. Labium ( Fig. 17 G) distally finely setose, palp without apophyses, marginally setose and with three distal spines. Maxillule ( Fig. 17 H) outer endite with eleven distal spines and two subdistal setae, inner endite with four plumose distal setae and outer subdistal apophysis; palp of two articles, distally with two setae. Maxilla ( Fig. 17 I) with smooth outer margin; outer lobe of moveable endite with two simple subdistal setae and five curved distal setae; inner lobe of moveable endite with three simple and three denticulate setae; outer lobe of inner endite distally with bifurcate, trifurcate and simple spines; inner lobe of fixed endite with rostral row of 13 setae guarding two longer setae. Maxilliped ( Fig. 17 J) basis with setule at mid-length; endites with two coupling hooks, five outer fusiform setae, distal margin with a mixture of spatulate spines and fine setae, caudodistal inner seta not seen; palp first article with inner sub-distal setae as long as second palp article; second article with outer distal slender spine, inner margin with about nine shorter curved setae in two rows and four longer setae; third article with six inner marginal curved setae; fourth article with two subdistal and five marginal setae. Epignath ( Fig. 17 K) wide, cup-like, distal spine naked.

Cheliped ( Fig. 18 A) slender, basis about twice as long as wide, ventral margin with proximal seta, stout spine at mid-length, three setae in distal half, one blunt with distal setule (damaged?); exopodite with four plumose setae on distal article; merus subrectangular with two setae on ventrodistal “shoulder”; carpus 4.3 times as long as wide, with one dorsodistal seta, ventrally with four marginal and two submarginal setae; propodus 1.5 times as long as wide, with one dorsodistal seta and two setae in junction of fingers; fixed finger shorter than palm of propodus, with three distal setae and row of fine setules along distal cutting edge, terminal spine distinct; dactylus with three distal setae; neither cutting edge with denticulations or apophyses.

Pereopod 1 ( Fig. 18 B) robust, coxa with large, rounded apophysis bearing three setae; basis stout, twice as long as wide, dorsally with array of eleven plumose marginal setae, ventrally with distal spine and simple seta; exopodite with five plumose setae on distal article; ischium compact with two ventrodistal setae; merus 0.6 times as long as basis, with four ventral marginal setae, one mid-distal seta and two dorsodistal setae, and single dorsodistal and ventrodistal spines; carpus 0.7 times as long as merus, with two ventral spines interspersed with simple setae, one dorsodistal spine amongst marginal row of setae; propodus 1.4 times as long as carpus, ventrally with five spines interspersed with simple setae, dorsally with two spines interspersed with simple setae in distal half; dactylus nearly twice as long as unguis, both together two-thirds as long as propodus, dactylus with two ventral denticulations and dorsodistal seta.

Pereopod 2 ( Fig. 18 C) basis 4.5 times as long as wide, naked; ischium with two ventrodistal setae; merus 0.2 times as long as basis, with two ventrodistal and one dorsodistal setae; carpus 1.9 times as long as merus, ventrally with one slender spine and three simple setae; propodus just shorter than carpus, with mid-dorsal penicillate seta and three longer and one fine shorter distal setae; dactylus slender with dorsodistal seta, dactylus and claw together 1.4 times as long as propodus. Pereopod 3 ( Fig. 18 D) similar to pereopod 2, but basis with ventroproximal seta and two ventrodistal setae, merus without dorsodistal seta, carpus as long as merus and without ventral spine but with three dorsodistal setae; propodus with two ventral and five distal simple setae.

Pereopod 4 ( Fig. 18 E) basis nearly three times as long as wide, with two mid-dorsal fine setae and two ventrodistal setae; ischium with two ventrodistal setae; merus with dorsodistal seta, ventrally with three setae in distal half; carpus 1.8 times as long as merus, with mid-ventral seta, ventrodistal spine and distal array of five setae; propodus 0.9 times as long as carpus with dorsoproximal penicillate seta, ventral and distal margins each with three setae; dactylus with mid-dorsal seta, together with unguis 0.7 times as long as propodus, proportionately shorter than on all other pereopods. Pereopod 5 ( Fig. 18 F) basis similar to pereopod 4, but with dorsoproximal penicillate seta and longer ventroproximal seta; ischium with two ventrodistal setae; merus with slender ventrodistal spine and single ventrodistal, mid-distal and dorsodistal setae; carpus with four dorsodistal setae but no spine; propodus ventral margin with two spines in proximal half and two setae in distal half, two dorsodistal setae; dactylus with unguis 1.3 times as long as propodus.

Pereopod 6 ( Fig. 18 G) similar to pereopod 4, but basis with two penicillate and three simple dorsoproximal setae, carpus with two slender ventral spines; propodus with ventral row of five short denticulate spines, five longer and three shorter distal setae, dactylus with unguis 1.4 times as long as propodus.

Pleopods ( Fig. 19 A) all alike, basis with naked outer margin, inner margin with one plumose seta; rami subequal, endopod with seven plumose setae around margins, exopod with eight marginal plumose setae but without setae on proximal inner margin.

Uropod ( Fig. 19 B) basis with two small outer-distal setae; exopod of four segments; endopod elongate, segmentation occasionally obscure, about one-third as long as total body length, with some 18 segments.

Description of male: Generally as female, including antennae and antennule. Cheliped ( Fig. 19 C) stouter than that of female, basis similar but with two plumose ventral setae; carpus 3.3 times as long as wide; chela forcipate, propodus stouter than that of female, with fixed finger attached subdistally, and shorter than dactylus. Pereopod 1 ( Fig. 19 D) similar to that of female, but basis with dorsodistal cuticular flange, propodus with only four ventral spines, dactylus apparently without denticulation.

Etymology: Named after Awang Alak Betatar who, according to legend, was the founder of Brunei, and became its first Sultan after his conversion to Islam in 1363.

Remarks: There were three described species of Bunakenia that have dorsal plumose setae on the basis of pereopod 1, on which character they were separated from those without such setae at the subgeneric level by Guţu (1996b). BłaŻewicz-Paszkowycz & Bamber (2012) dispensed with these subgenera on finding the south-eastern Australian species B. labanticheiros BłaŻewicz-Paszkowycz & Bamber, 2012 which had such setae in the male, but not in the female.

Bunakenia betatari sp. nov. is the fourth species of the genus to have plumose basis setae on pereopod 1 in the female. It is distinguished from B. salzella Bamber, 2005 and B. tanzaniana Guţu, 1996 (b) in having only three (as distinct from six) dorsal plumose setae on the carpus of pereopod 6, only one (as distinct from three) inner marginal seta on the basis of the pleopod, three (as distinct from 4 or 5) segments in the antennular accessory flagellum, and only two (as distinct from five) maxillule palp distal setae, inter alia.

Bunakenia betatari is distinguished from the generotype, B. indonesiana , in having a dorsodistal spine on the merus of pereopod 1 (none in B. indonesiana ), only two ventrodistal setae on the cheliped merus in the female (six), two maxillule palp distal setae (three), fewer setae on the mandibular palp articles and on the antennal squama, and fewer segments in the antennular main flagellum; further, the male of B. indonesiana has a flange on the merus of pereopod 1, whereas the male of B. betatari has a flange on the basis but not on the merus (as well as a much more slender carpus on the cheliped).

The distal conformation of the mandibular molar in Bunakenia betatari is unique in the genus.

It is unusual that the propodus of pereopod 1 of the male has one less ventral spine than does that of the females (all females examined had five such spines). Esquete et al. (2012a; 2012b) found that this character was intraspecifically invariable in two species of Apseudopsis , as it seems to be throughout the Apseudidae . Whether it is an example of sexual dimorphism or a teratological feature of the single male in the present material, can only be resolved by finding further male specimens of this species.

Figures

FIGURE 17. Bunakenia betatari sp. nov.: A, holotype female, dorsal; B, antennule; C, antenna; D, labrum; E, left mandible; F, right mandible; G, labium; H, maxillule; I, maxilla; J, maxilliped; K, epignath. Scale line = 0.1 mm for A, 0.2 mm for B to K.

FIGURE 18. Bunakenia betatari sp. nov.: A, cheliped; B to G, pereopods 1 to 6 respectively. Scale line = 0.2 mm.

FIGURE 19. Bunakenia betatari sp. nov.: A, pleopod (plumose nature of all setae not shown); B, posterior of pleotelson and right uropod; C, cheliped of male; D, pereopod 1 of male. Scale line = 0.2 mm.