Pseudoleptochelia occiporta, Błażewicz-Paszkowycz & Bamber, 2012

Błażewicz-Paszkowycz, M. & Bamber, R. N., 2012, The Shallow-water Tanaidacea (Arthropoda: Malacostraca: Peracarida) of the Bass Strait, Victoria, Australia (other than the Tanaidae), Memoirs of Museum Victoria 69, pp. 1-235 : 119-125

Pseudoleptochelia occiporta sp. nov.

Figures 79–82

Material examined. 1 (J58467), holotype, 1 (J58468), allotype, 48

, 2 juveniles (J55820), paratypes, Stn 81-T-1 162, 40º09.2'S 147º31.9'E, 51 m depth, shelly sand, 14 November 1981, coll. R.S. Wilson, RV Tangaroa . 4, 2 juveniles (J50804), paratypes, Stn VC 23 C1, 38º19.18'S 144º37.62E, 40 m deep, reef, 12 May 1998. 10 specimens (J48183), paratypes, CPBS 01 S/4, 38º21.73'S 145º13.23'E, 3 m depth, 1 April 1965 . 6 specimens, (J48188), paratypes, CPBS 03 S/2, 38º21.65'S 145º15.21'E, 2 m depth, sandy-mud, 13 April 1965 . 25 specimens, (J48175), paratypes, CPBS 11 N/4, 38º23.23'S 145º13.28'E, 5 m depth, fine sand, 21 March 1965 . 10 specimens, (J48178), paratypes, CPBS 11 S/2 , 1 specimen, (J48751), paratypes, CPBS 11 S/4, both 38º22.00'S 145º13.38'E, 3 m depth, shelly gravel, 17 March 1965 . 5 specimens, (J48755), paratypes, CPBS 22 N/4, 38º20.60'S 145º13.46'E, 13 m depth, shelly sand, 18 March 1965 . 66, 26 juveniles, (J48967), paratypes, CPBS 32 N/367, 38º20.83'S 145º13.49'E, 13 m depth, sandy gravel, 20 March 1967 . 1 (J48972), 3 specimens (J48970), paratypes, CPBS 32 N/769, 38º20.83'S 145º13.49'E, 13 m depth, sandy gravel, 15 July 1969 . 12 specimens, (J48971), paratypes, CPBS 32 N/870, 38º20.83'S 145º13.49'E, 13 m depth, sandy gravel, 12 August 1970 . 20, 10 juveniles, (J48980), paratypes, CPBS 32 S/770, 38º21.60'S 145º13.67'E, 13 m depth, muddy sand, 6 July 1970 . 8 specimens, (J48974), paratypes, CPBS 32 S/866, 38º21.60'S 145º13.67'E, 13 m depth, muddy sand, 26 August 1966 . 1, (J48955), paratypes, CPBS 40 O/3, 38º21.17'S 145º14.00'E, 15 m depth, sand, 1 April 1965 . 3 specimens, (J48958), paratypes, CPBS 41 N/2, 38º20.81'S 145º13.85'E, 13 m depth, gravelly sand, 30 March 1965 .

Description of female. Body ( Fig. 79A, B, C, D) relatively small for the genus, holotype 2.7 mm long, 6.3 times as long as wide. Cephalothorax subrectangular, tapering towards anterior, 1.4 times as long as wide, 1.5 times as long as pereonites 1 and 2 together, with slight rostrum, eyelobes rounded, eyes present and black, paired setae at posterior of eyelobes and single setae midlaterally. Pereonite 1 shortest, pereonite 2 and 6 subequal and 1.5 times as long as pereonite 1, pereonites 3 to 5 subequal and 1.9 times as long as pereonite 1 (all pereonites respectively 2.6, 1.8, 1.4, 1.4, 1.5 and 1.7 times as wide as long). Pleon with five free subequal pleonites bearing pleopods; each pleonite about 5.3 times as wide as long, with single midlateral setae. Pleotelson pentangular, as long as last two pleonites together, 1.6 times as wide as long, with one anterolateral and two posterolateral setae on each side and two distal setae.

Antennule ( Fig. 80A) of three longer and one minute distal articles, proximal article 3.5 times as long as wide, 1.5 times as long as distal three articles together, with proximal, mesial and distal inner groups of penicillate setae, inner simple mesial seta, and one outer and one long inner distal seta longer than second article; second article twice as long as wide, one-third as long as first article, longer distal seta just longer than article; third article just shorter than second, distally with one simple and one penicillate seta; fourth article minute, distally with three simples and two penicillate setae and one aesthetasc.

Antenna ( Fig. 80B) of six articles, proximal article compact, naked; second article as long as wide, with single inner distal and dorsodistal slender spines; third article as long as second and just longer than wide, with dorsodistal stouter spine ( Fig. 80 b'); fourth article longest, 3.8 times as long as wide and twice as long as third, with short mesial setae and distal tufts of penicillate and simple setae; fifth article 0.7 times as long as fourth; sixth article minute with six distal setae.

Labrum ( Fig. 80C) hood-shaped, setose. Left mandible ( Fig. 80D) with crenulate lacinia mobilis wider than distal end of mandible, distal crenulation on pars incisiva, pars molaris with strong rugosity; right mandible ( Fig. 80E) similar but without lacinia mobilis, crenulation of pars incisiva extending down inner margin. Labium ( Fig. 80G) wide, bilobed, distally finely setose, without palp. Maxillule ( Fig. 80F) with nine distally bifurcate spines and setose margins, rows of setules on inner distal face; palp distinct, with two distal setae. Maxilliped ( Fig. 80H) palp first article naked, second article with finely setose inner margin, and with one outer and two inner setae, distal-most inner seta not reaching distal margin of third palp article; third and fourth articles with 11 inner marginal setae in two rows of 7 (dorsal) and 4 (ventrodistal); fourth article with one outer subdistal seta; basis with 4 to 6 long setae (sometimes asymmetrical – Fig. 80 H') extending to distal edge of second palp article; endites ( Fig. 80H ") distally with fine outer setules, long outer seta and three robust spatulate spines, with additional subdistal pair of spatulate spines.

Cheliped ( Fig. 81A) with rounded, comparatively stout basis 1.6 times as long as wide, with subdistal dorsal seta; merus triangular with three ventral setae; carpus 1.7 times as long as wide, with three midventral setae and three shorter dorsal marginal setae; propodus as long as wide, with dorsodistal seta and one seta at base of dactylus; fixed finger with five ventral and three inner setae, cutting edge crenulate, subdistal claw; dactylus with finely-crenulate cutting edge.

Pereopod 1 ( Fig. 81B) longer than other pereopods, coxa with long seta; basis slender, 4.4 times as long as wide, with single dorsoproximal simple and penicillate setae; ischium compact with one ventral seta; merus 0.9 times as long as carpus, with one dorsodistal and two ventrodistal setae; carpus with distal crown of two dorsodistal, one inner and two outer medial, and one ventrodistal setae, longest of which is much less than half length of propodus; propodus 1.5 times as long as carpus, with three setae on subdistal dorsal mound and one subdistal ventral seta; dactylus slender, curved, extending into shorter slender unguis 0.7 times as long as dactylus, the two together some 1.4 times as long as propodus. Pereopod 2 ( Fig. 81C) more compact than pereopod 1; basis 2.45 times as long as wide; ischium with 2 setae; merus just longer than carpus and 1.1 times as long as wide, with single dorsodistal and ventrodistal setae and tooth-like ventrodistal spine and ventral rows of microtrichia; carpus with two dorsodistal and single ventrodistal setae and two small ventrodistal spines, and ventral rows of microtrichia; propodus 1.9 times as long as carpus, with three distal setae and dorsodistal sharp apophysis; dactylus and shorter unguis curved, together 0.6 times as long as propodus. Pereopod 3 ( Fig. 81D) similar to pereopod 2, but merus and carpus with no and one dorsodistal setae, propodus with two distal setae.

Pereopod 4 ( Fig. 81E) basis stout, 1.7 times as long as wide with two ventroproximal penicillate setae; ischium with two ventrodistal setae; merus with paired ventrodistal spines and ventral rows of microtrichia; carpus just shorter than merus, with one dorsodistal seta, outer, ventral and inner distal spines each with fine subdistal setules, and ventral rows of microtrichia; propodus 1.1 times as long as carpus, with two ventrodistal spines, three dorsodistal setae mostly as long as dactylus, serrated spines adjacent to dactylus articulation, and ventral rows of microtrichia; dactylus and distinct unguis curved, 0.6 times as long as propodus, dactylus with microtrichia. Pereopod 5 as pereopod 4. Pereopod 6 ( Fig. 81F) as pereopod 4, but propodus with four shorter and one longer distal setae.

Pleopods ( Fig. 81G) all alike, typical for the genus, basis naked, endopod with single inner plumose seta and proximal outer seta separated from remainder.

Uropod ( Fig. 81H) biramous, basis naked; exopod of two segments, as long as proximal endopod segment, outer distal seta longer than inner distal seta; endopod of five or six segments, distal segments slender.

Description of male. Smaller than female (allotype length 1.5 mm), body ( Fig. 79E) more compact, cephalon 1.25 times as long as pereonites 1 to 3 together, with large eyelobes bearing large black eyes; pereonite 1 shortest, pereonite 2 just longer, pereonites 3 and 6 subequal, 1.8 times as long as pereonite 1, pereonites 4 and 5 twice as long as pereonite 1. Five free pleonites, subequal in length, as long as pereonite 1, pleotelson as long as pleonites 4 and 5 together. Pleotelson with much longer distal setal pair ( Fig. 82K).

Antennule ( Fig. 82B) first peduncle article 2.4 times as long as wide, with paired dorsomedial penicillate setae and single dorsodistal penicillate and simple setae; second article 0.65 times as long as first with single ventroproximal and dorsal subdistal simple setae; third article 0.3 times as long as second with single ventrodistal simple seta; flagellum of 8 segments, segment 1 with proximal and distal rows of aesthetascs, segments 2 to 7 bearing distal row of 5 or 6 aesthetascs, segment 8 minute, distally with four simple setae.

Antenna ( Fig. 82C) of six articles, proximal article compact, naked; second article longer than wide, longer than first article, with single dorsoproximal and three distal seta; third article shorter than second, 1.6 times as long as wide, with single simple distal seta; fourth article nearly twice as long as third, with mesial seta and distal tufts of penicillate and simple setae; fifth article as long as fourth with two long distal setae; sixth article minute, with three simple distal setae.

Mouthparts atrophied.

Cheliped ( Fig. 82A) with subchelate chela; basis twice as long as wide; merus short, with seven ventral setae; carpus 1.9 times as long as wide but with large subtriangular ventral apophysis bearing the three midventral setae, dorsal margin with continuous row of nine setae; propodus twice as long as wide with dorsodistal seta, fixed finger reduced to small apophysis with claw, with three ventral setae, three setae adjacent to remains of cutting edge, inner diagonal comb-row of ten shorter and one longer setae; dactylus slender, curved, as long as propodus, with row of four setae along cutting edge.

Pereopods ( Fig. 82D to I) similar to but more slender than those of female, with in particular more elongate propodi; merus shorter than carpus on pereopods 1 to 3; on pereopods 4 to 6 propodus much longer than carpus, ventrodistal merus spines more elongate than those of female, dactylus proportionately longer than in female.

Pleopods ( Fig. 82J) with longer setae than on those of female. Uropod ( Fig. 82K) basis with inner distal row of setae; exopod two-segmented, longer than proximal endopod segment; endopod of five segments, less-elongate and more heavily setose than that of female.

Distinctions of manca. Smaller than female ( Fig. 79B), similar in morphology and proportions, uropod exopod of one segment.

Etymology. From the Latin occidentalis – western, and portus – a port, the species mainly occurring in, and common in, Western Port, Victoria.

Remarks. The genus Pseudoleptochelia is in need of review. Bird & Bamber (2000) listed twelve species in the genus, since when three further species have been described, P. fairgo Bamber, 2005 , and P. straddi Bamber, 2008 , both from Australia, and P. bulbus Bamber, 2006 from New Caledonia. However, the male of P. bulbus , and P. straddi (known only from the male) are currently suspected to be species of a different genus (Bamber, in prep.). Many of these Pseudoleptochelia species are poorly described, particularly their females and their mouthparts, some being known only from males.

Lang (1973) diagnosed the genus Pseudoleptochelia as having stout posterior pereopod bases, with spines on the second and third antennal peduncle articles (as in Leptochelia ), the uropod exopod with one or two segments, the endopod with at least three segments, and the maxilliped bases with two distal setae. Unfortunately, Lang (ibid.) based his genus on Heterotanais anomalus Sars, 1882 , the female of which is not fully described, and on his own new species, Pseudoleptochelia mortenseni , which, judging from his figure 16, is clearly a chimaera, as the antennule of “a small female” (Lang, 1873: fig. 16g) is typical of a species of Konarus Bamber, 2006 or Parakonarus Bird, 2011 , and not Pseudoleptochelia sens . auctt., casting doubt on with which female his subchelate male should be associated (see Bird, 2011). In practice, the maxilliped-basis setation and female antennal spination are unknown in at least half of the Pseudoleptochelia species.

Pseudoleptochelia occiporta sp. nov. is consistent with the generic diagnosis of Lang (loc. cit.) except for its having 4 to 6 maxilliped-basis setae, a feature of three other leptocheliid genera, Leptochelia , Konarus and Parakonarus . It shares this feature, as well as the five distal spatulate spines on the maxilliped endite, with P. bulbus Bamber, 2006 from New Caledonia, a species differing owing to its one-segmented uropod exopod and distinct setation of the pereopod 1 carpus, inter alia.

The genera Konarus and Parakonarus both have setae rather than spines on the second and third antennal peduncle articles, and an unguis distinctly longer than the dactylus on pereopod 1, unlike the present species. We therefore choose to place the present species in Pseudoleptochelia until the genus has been properly resolved.

The only currently accepted species of Pseudoleptochelia recorded previously from Australia is P. fairgo , known from Esperance, Western Australia, and Brisbane, Queensland (Bamber, 2005; 2008). The female of P. fairgo , which also has four maxilliped-basis setae, is unique in the genus in having setose tubercles on the merus of pereopods 4 to 6, and a tuft of elongate setae on the cheliped carpus pointing proximally in life, neither feature being present in P. occiporta .

The male of the present species has a rounded apophysis on the carpus of the cheliped like Pseudoleptochelia fairgo , but differs from that species in that P. fairgo has a ventrodistal apophysis on the propodus of the cheliped which is wider and rounded (slender and pointed in P. occiporta ) and a strong dorsodistal seta on the third antennular peduncle article as long as the proximal four flagellum segments (only a very small dorsodistal seta in P. occiporta ). In P. occiporta the uropod exopod is two-segmented in both sexes, but the exopod in P. fairgo is one-segmented with only an incipient fusion line. Of the four Pseudoleptochelia species having a two-segmented uropod exopod, none have a ventral carpal apophysis on the male cheliped as found in P. occiporta .

Pseudoleptochelia occiporta was taken at depths between 3 and 51 m, on gravelly to muddy sands, mainly in Western Port.