Macrostylis meteorae, Brandt, Angelika, 2004

Brandt, Angelika, 2004, New deep­sea species of Macrostylidae (Asellota: Isopoda: Malacostraca) from the Angola Basin off Namibia, South West Africa, Zootaxa 448, pp. 1-35 : 21-25

Macrostylis meteorae sp. nov. ( Figs 12–13 )

Holotype: Ovig. Ψ (2.2 mm), Angola Basin, South Atlantic, 16°18.1’S 005°27.2’E – 16°19.3’S 005°27.2’E, 28 July 2000, ZMH K­ 40282; EBS, station 348, 5387– 5390m.

Paratypes: Ovig. 2 Ψ (2.2, 2.5 mm), ZMH K­ 40283; EBS, station 348, station data as for holotype. 1 Ψ (2.5 mm), 1 ovig. Ψ (2.3 mm), 16°14.3’S 005°26.8’E – 16°14.9’S 005°26.7’E, 29 July 2000, ZMH K­ 40698, EBS station 350, 5389 m.

Distribution: Only known from Angola Basin, 5387–5390 m.

Etymology: Named after the research vessel “Meteor” from which the species was collected.

Diagnosis: Head sub­quadrate, 1.2 as long as wide, female operculum trapezoidal.

Description: Female (holotype) body ( Fig. 12 ) 3 times as long as wide; body dorsum and margins smooth, without setae, few setules caudally on pleotelson. Head sub­quadrate, 1.2 as wide as long, without dorsal spines or any sculpture. Pleotelson 1.4 as long as wide, of quadrangular shape, caudally slightly convex. Pereonites 5 and 6 longest, pereonites 1– 3 shortest. Uropods 1.7 pleotelson length.

A1 ( Fig. 12 ): less than 0.1 as long as body, of 5 articles. Article 1 longest, with 1 simple seta. Article 2 0.25 as long as first, with 2 broom setae, articles 3 to 5 decreasing in length and width, last article with 1 aesthetasc and 1 simple seta.

A2 ( Fig. 12 , dorsal view): 0.2 as long as body, with 5 peduncular and 6 flagellar articles. Peduncular articles 1–3 short, peduncular article 5 longest. Flagellar articles of about the same size, tip of flagellum with 3 simple setae.

LMd ( Fig. 12 ): Incisor with 5 teeth, lacinia mobilis 0.6 as long as incisor, bearing 3 teeth, spine row of 9 setae, pars molaris stout, tapering distally, with 8 simple setae of various lengths. Mandibular palp absent.

RMd ( Fig. 12 ): Similar to left, but incisor only with 3 teeth, lacinia mobilis with some branches, spine row with 12 members.

Mx1 (not illustrated): Inner endite 0.4 as wide as outer endite. Outer endite with 11 strong spine­like setae, inner endite with 1 strong simple seta.

Mx2 ( Fig. 12 ): 3 Endites, outer and medial endites most slender, with 3 long setae, medial endite with at least 8 distal setae.

Mxp ( Fig. 12 ): Endite reaching 0.7 of length of second palpal article, with 4 fan and several simple setae distally and 1 mediodistal simple spine­like seta, 2 medial coupling hooks. Palp length 0.5 as long as basis length. First palp article shortest, quadrangular, with 1 distomedial simple seta; article 2 broadest and longest, with 1 distodorsal simple seta and 2 distomedial ones; article 3 0.6 as wide as article 2, with 5 medial and 1 lateral simple setae, article 4 narrow, 0.3 as wide as article 3, with 2 simple distal setae, last article narrowest, as long as fourth, with 3 simple setae. Epipod 4.0 as long as wide, epipod almost as long as basis, lateral angular projection at proximal third of length, distally few short setules.

P1–P4 ( Figs 12 , 13 ): P1–3 slightly increasing in lengths, P4 ( Fig. 13 ) shortest. Bases of all pereopods longest articles, of P1 and 2 with 4 broom setae, of P2 with 9, of P3 with 3 and P4 with 5 broom setae, few simple setae, ischia about 0.5–0.7 basis length with varying numbers of sensory setae on both margins, P3 with 5 long ones distodorsally. Meri slightly shorter than ischia, in P1 and P2, in P3 and P4 of same length, with long sensory setae, especially distodorsally, on P3 with row of 6 long sensory setae distodorsally on merus. Carpi slightly longer than meri in P2 and P4, in P1 and P3 as long as meri, with sensory setae on both sides, on P2 and P3 especially on dorsal side, 1 distodorsal broom seta on P2 and P4. Propodi 0.4–0.6 as long as carpi, with few setae. Dactyli with 2 claws.

P5 and P6 ( Figs 13 ) (P 6 broken off in this specimen): Long and slender, basis longest article, with 5 broom setae and 2 simple setae in P5, in P7 with 15 long whip setae and 5 ventral simple ones. Ischium of P5 and P7 0.8 as long as basis, with 3 (P7 with 6) sensory setae. Merus 0.8 as long as ischium, with 5 sensory setae in P5, in P7 with 4 ventral ones and 5 distodorsal sensory setae. Carpus longer than merus and propodus, with 5 sensory setae in P5 and seven in P7, and 1 broom seta distodorsally in P5. Propodus of P5 with 5 sensory setae on both sides, P7 only 3 setae, but ventral setae being very long, 1 distodorsal broom seta. Dactylus shorter than propodus, with 2 long claws of different lengths, in P7 distally serrated.

Plp 2 ( Fig. 13 ): Elongate, trapezoidal, broadest medially, with 10–12 proximolateral whip setae, 3 mesiolateral setae and few dorsal setules, distally with 11 plumose setae.

Plp 3 ( Fig. 13 ): Endopod much longer than wide, almost rectangular, with 4 distal plumose setae, exopod almost as long as endopod, laterally and distomedially with small setules.

Plp 4 ( Fig. 13 ): Endopod almost quadrangular, bare, twice as long as wide, exopod 0.6 as long as endopod, distally with 1 long plumose seta.

Pleopod 5 (Fig. 24) only 1 small oval lobe.

Urp ( Fig. 13 ) Sympod 2.5 times as long as ramus, with 3 broom, 1 plumose and 4 simple setae, ramus with 7 broom setae of different lengths and 2 long simple setae.

Remarks. Macrostylis meteorae sp. nov. is similar to M. hirsuticaudis Menzies, 1962 , but the antennule of the new species is smaller and possesses only one aesthetasc, the head is narrower than in M. hirsuticaudis and the ischium of pereopod 3 possesses five dorsal sensory setae in M. meteorae in contrast to seven setae in M. hirsuticaudis . Moreover, the female operculum of M. meteorae is almost trapezoidal, a character state not reported for any other species of Macrostylis . Serrate dactylar claws are also present in M. longispinis sp. nov., but that species can easily be distinguished by the long, caudally directed ventral spine on pereonite 7.

Figures

FIGURE 12. Macrostylis meteorae sp. nov. holotype Ψ (2.2 mm), dorsal view, antennule, antenna, left and right mandibles, maxilla, maxilliped, pereopods 3, 7.

FIGURE 13. Macrostylis meteorae sp. nov. holotype Ψ (2.2 mm), pereopods 1, 2, 4, 5, pleopods 2 – 5, uropod.