Parakonarus sozo, Bamber, 2013

BAMBER, ROGER N, 2013, A re-assessment of Konarus Bamber, 2006 and sympatric leptocheliids from Australasia, and of Pseudoleptochelia Lang, 1973 (Crustacea: Peracarida: Tanaidacea), Zootaxa 3694 (1), pp. 1-39 : 23-28

Parakonarus sozo sp. nov.

Figs. 10–12

Pseudoleptochelia mortenseni Lang, 1973 , Fig. 16g –j (part), non- P. mortenseni Lang, 1973 sensu stricto (= Leptochelia mortenseni ).

Material: One female, holotype (ZMUC-CRU- 20533), one male, allotype (ZMUC-CRU-20534), 15 females, one male, eight neuters, paratypes (ZMUC-CRU-20535), all ex ZMUC-CRU-4396; one male (fragments; figured specimen of Lang, 1973), paratype (ZMUC-CRU-20536), ex ZMUC-CRU-7400. “ Tobago ”. Zoological Museum , University of Copenhagen .

Etymology. From the Greek sozo —to save, to rescue, having rescued this taxon from its being subsumed within Lang’s (1973) Pseudoleptochelia mortenseni (noun in apposition).

Description of female. Holotype body ( Fig. 10A ) 1.3 mm long, 5.8 times as long as wide. Cephalothorax elongate, subrectangular but with convex margins narrowing towards anterior, 1.3 times as long as wide, almost as long as pereonites 1 to 3 together, with slight rounded rostrum, rounded eyelobes conspicuous, eyes present and black, one lateral seta at posterior of each eyelobe; dorsal cuticular lines distinguishing carapace not seen. Each pereonite and pleonite with single anterolateral seta on each side. Pereonite 1 shortest, pereonite 2 just longer than pereonite 1, pereonites 3 to 5 subequal, 1.7 times as long as pereonite 1, pereonite 6 shorter, 1.5 times as long as pereonite 1; all pereonites wider than long, respectively 2.8, 2.4, 1.7, 1.5, 1.4 and 1.8 times as wide as long. Each pleonite about 4.7 times as wide as long. Pleotelson semicircular, nearly twice as long as each pleonite, 2.6 times as wide as long, with paired anterolateral, laterodistal and distal setae ( Fig. 12A ).

Antennule ( Fig. 10C ) of four articles, including distal cap-like segment; proximal article tumid, twice as long as wide, 1.4 times as long as distal three articles together, with one long and one shorter distal outer simple setae, single medial inner and outer simple setae, and median outer and distal inner penicillate setae; second article as long as wide and 0.25 times as long as first article, inner distal seta longer than article; third article three times as long as wide and 1.8 times as long as second article, with two simple distal setae; fourth article minute, with three simple distal setae and one aesthetasc.

Antenna ( Fig. 10D ) proximal article compact, naked; second article 2.4 times as long as first, 1.3 times as long as wide, with fine ventrodistal seta, longer dorsodistal seta and crenulate dorsal margin; third article as long as wide, 0.7 times as long as second article, with single dorsal distal seta; fourth article longest, 1.4 times as long as second article and three times as long as wide, with single seta at mid-length and three distal setae; fifth article almost as long as second and with two distal simple setae; sixth article minute, with four distal setae.

Labrum (not figured) typical for the genus, lobate, distally setose. Left mandible ( Fig. 10F ) with crenulate lacinia mobilis, simple pars incisiva, pars molaris truncate, blunt, with some marginal distal rugosity; right mandible ( Fig. 10E ) similar but without lacinia mobilis, pars incisiva not crenulate, tip slightly bifid. Labium (not figured) typical for the genus, wide, bilobate, distally finely setose. Maxillule ( Fig. 10G ) with nine distal spines, distally setose outer, inner and mesial margins; palp distinct, with two distal setae. Maxilla not seen. Maxilliped ( Fig. 10H, I ) palp first article naked, second article with one outer and four inner setae, distal-most inner seta almost reaching distal margin of third palp article; third article with inner row of three setae and submarginal row of three setae; fourth article with distal row of five simple setae and one outer subdistal seta; basis with two unequal distal setae, outer seta longest but not extending to tip of second palp article; each endite ( Fig. 10I ) distally with single outer seta, two elongate spatulate spines, and one rounded inner spine with slight marginal crenulations. Epignath ( Fig. 10J ) typical for the subfamily, elongate, slender, setose.

Cheliped ( Fig. 11A, B ) stout; coxal sclerite with two (?) outer setae; basis 1.5 times as long as wide, with mesial dorsodistal slender seta mounted on tubercle; merus triangular with four ventral setae; carpus 1.3 times as long as wide, outer margin extended ventrodistally and distally to form slight cuff around base of propodus, with five fine dorsal marginal setae, ventral margin with three setae; propodus as long as wide, outer distal margin extended into apophysis bearing strong seta, inner comb-row of two spines with adjacent microtrichia; fixed finger 0.8 times as long as propodus, with two ventral setae and three inner setae, cutting edge crenulate, terminal spine subdistal; dactylus simple with proximal seta less than half as long as dactylus.

Pereopod 1 ( Fig. 11C ) longer than other pereopods, coxa with long seta; basis curved, 3.3 times as long as wide, with dorsoproximal seta longer than basis width; ischium with two unequal setae; merus 0.4 times as long as basis, naked; carpus 1.7 times as long as merus, with three distal setae, longest of which is more than half length of propodus; propodus 1.1 times as long as carpus, with one ventral and three dorsal subdistal setae, and fine ventrodistal seta; dactylus slender, with dorsoproximal seta almost reaching tip of dactylus, curved unguis 1.9 times as long as dactylus, the two together 1.4 times as long as propodus.

Pereopod 2 ( Fig. 11D ) more compact than pereopod 1; basis 2.7 times as long as wide, apparently naked; ischium with two unequal setae; merus about one-third as long as basis, naked; carpus 1.4 times as long as merus, with single dorsodistal seta; propodus 1.2 times as long as carpus, with paired subdistal setae longer than dactylus plus unguis; dactylus 1.4 times as long as unguis, both together half as long as propodus. Pereopod 3 as pereopod 2.

Pereopod 4 ( Fig. 11E ) basis stout, 1.8 times as long as wide, with dorsoproximal penicillate seta; ischium compact, with two unequal ventrodistal setae; merus one-third as long as basis, with two ventrodistal tuberclemounted setae and adjacent rows of microtrichia; carpus as long as merus, with one ventrodistal and single outer and inner distal compact spines and ventral rows of microtrichia; propodus 1.1 times as long as carpus, with paired ventrodistal spines and three dorsodistal setae, two of which are longer than dactylus plus unguis; dactylus and minute unguis not fused into an claw, curved, 0.7 times as long as propodus. Pereopod 5 as pereopod 4. Pereopod 6 ( Fig. 11F ) similar to pereopod 4, basis apparently naked, carpus with single dorsodistal seta; propodus with three longer dorsodistal setae and two shorter distal setae.

Pleopods (not figured) all alike, typical for the genus; endopod with single inner and nine outer plumose setae, exopod with 13 marginal setae.

Uropod ( Fig. 12A ) basis naked; exopod of one segment, longer than proximal endopod segment, outer distal seta longer than inner distal seta; endopod of four segments, fourth segment longer than others.

Male ( Fig. 10B ) similar to but little shorter than female, pleon proportionately longer, cephalothorax proportionately narrower. Antennulae and chelipeds dimorphic, as figured by Lang (1973: fig. 16h and 16j respectively); cheliped carpus with mid-ventral setose apophysis, propodal comb-row with 11 spines. Posterior pereopods ( Fig. 12B, C ) more slender than those of female; merus and carpus with simple ventrodistal spines, propodus more elongate, dactylus with distal fringe of fine setules.

Remarks. This material represents the males and “small” females of Lang’s (1973) Pseudoleptochelia mortenseni . The antennule of the female is compact and has a distal cap-like flagellar segment, the antenna has setae rather than spines on the second and third peduncular articles, the cheliped has dorsal marginal spinules, the meri of the posterior pereopods bear setose tubercles, the uropod exopod has only one segment, the male cheliped carpus has a mid-ventral apophysis ( Lang, 1973, fig. 16j), and the posterior pereopods of the male have distal setules on their dactyli, all features in accord with Parakonarus , rather than Konarus or Pseudoleptochelia as restricted herein.

No plates or sutures were evident in the carapace, but the material has been in preservative for at least forty years, so evidence of such structures is presumed to have disappeared.

This is the smallest konariin species known to date, which may account for its reduced setation, notably on cheliped merus and on the maxilliped (for example, basis with only two distal setae); equally, owing to the small size of the material, some of the subtler setation, such as the number of setae on the coxal sclerite, may have been misinterpreted. In addition to these distinctions, the cheliped is more compact than any other species of Parakonarus , and the male antennule is more compact than any of the other three well-described species.

With its geography ( Tobago, in the West Indies) it is quite remote from the other five well-described species (all Antipodean) and from P. provincialis (Mediterranean) .

Figures

FIGURE 10. Parakonarus sozo sp. nov., A, holotype female, dorsal; B, allotype male, dorsal; C to J—female paratype: C, antennule; D, antenna; E, right mandible; F, left mandible; G, maxillule; H, maxilliped; I, maxilliped endites, with detail of distal spines; J, epignath. Scale line = 0.4 mm for A and B, 0.1 mm for C to J.

FIGURE 11. Parakonarus sozo sp. nov., female: A, left cheliped; B, distal articles of right cheliped; C, pereopod 1; D, pereopod 2; E, pereopod 4; F, pereopod 6. Scale line = 0.1 mm.

FIGURE 12. Parakonarus sozo sp. nov., A, part of pleotelson and right uropod; B, pereopod 4 of male; C, pereopod 6 of male. Scale line = 0.1 mm.

FIGURE 16. Pseudoleptochelia anomala, male. A, right cheliped; B to G, pereopods 1 to 6 respectively. Scale line = 0.2 mm.