Mexicope sushara, Bruce, Niel L., 2004

Bruce, Niel L., 2004, Mexicope sushara sp. nov., the first New Zealand record of the isopod crustacean family Acanthaspidiidae (Asellota), Zootaxa 489, pp. 1-11 : 3-10

Mexicope sushara sp. nov. ( Figs 1–5 )

Material examined.— Holotype. ɗ (2.3 mm), Otago Shelf, 45°46.498–615’S, 170°54.752’E, 27 March 2003, 80– 81 m, on Hippomenella vellicata , coll. Anna Wood ( NIWA 3297). Paratypes. Ψ (ovigerous 3.5 mm, dissected), same data as holotype ( NIWA 3299). Ψ (2.1 mm, poor condition), Otago Shelf, 45°46.737’S, 170°54.578’E, 19 August 2003, 75 m, on Cinctopora elegans, coll. Anna Wood ( NIWA 3298).

Diagnosis: Mandible palp present, articles 2 and 3 partially fused. Median rostral spine present; preocular spines large, flat. Pereonites 2–4 strongly bifurcate laterally. Dorsal segments each with pair of submedian glass­like RS. Pleotelson 1.2 times as wide as long.

Description of holotype: Body twice as long as wide. Head 3.4 times as wide as long (excluding rostral spine); inter­antennal margin convex, with short median rostral spine. Pereonite 1 anterolateral projections acute, curved, forwardly directed; pereonites 2–4 distinctly bifid, projections subequal in size; pereonites 5 and 6 lateral projections posteriorly directed, falcate; pereonite 7 lateral projection triangular; pereonites 2, 3, 6 and 7 each with group of anteriorly directed long dorsal setae, those on pereonites 2 and 3 on the posterior lateral lobe. Mid­sternal spine present on sternite 7 only. Pleotelson 1.2 times as wide as long, proximal one­quarter narrow, widening abruptly, curving smoothly to submedian concavities and weak apical lobe; lateral margins irregular, with 3 or 4 posteriorly curved RS.

Antennule peduncle articles 1 and 2 of subequal length, article 1 2.3 times as long as wide, article 2 3.2 times as long as wide, article 3 0.3 times as long as article 2; flagellum of 6 articles, article 1 short, articles 2 and 3 of subequal length, each twice as long as wide, articles 5–6 becoming progressively shorter. Antenna peduncle scale about 1.5 times as long as article 4, with 3 apical and 1 sub­apical setae; peduncle article 5 4.3 times as long as wide, article 6 4.6 times as long as wide, 6 slightly longer (1.08) than 5, both with numerous long simple setae, dorsodistal angle of article 6 with distinct triangular lobe; flagellum with conjoint article 1 as long as remaining 12 articles, articles provided with transverse rows of long simple setae.

Mandible incisors both with 4 cusps; left lacinia mobilis with 4 cusps, basally with simple spine and robust distally serrate spine basally fused to body of lacinia mobilis; left spine row of 5 deeply­serrate spines and 8 simple setae, right spine row with 8 distally deeply­serrate spines; molar tapering, apex subtruncate with 2 long setae and small spines (right) or with ventral acute lobe and 4 long setae (left), both with apical fine setae; mandible palp articles 2 and 3 partly fused, article 3 with 3 serrate apical setae. Maxillule lateral lobe with 12 stout RS, most with few prominent serrations; mesial lobe simple, with 1 or 2 setae (broken in specimen) and numerous long scale­setae. Maxilla lateral and middle lobes each with 2 long and 2 short strongly serrate setae; mesial lobe with 4 sinuate circumplumose RS; all lobes basally with long scale­setae. Maxilliped basis 2.1 times as long as greatest width, distal margin 1 simple and 3 serrate RS; epipod linguiform 0.5 times as long as basis; palp article 2 distomesial margin weakly lobate, with 3 simple setae, article 3 distomesial margin with 2 simple setae, article 4 2.5 times as long as wide with transverse row of 5 long simple setae, article 5 0.3 times as long as article 4 distal margin with 8 simple setae.

Pereopods all with similar setation, anterior pereopods (1–3) proportionally shorter than posterior pereopods (4–7), most of the additional length resulting from longer propodus. Pereopod 1 basis 4.2 times as long as greatest width; ischium 0.5 times as long as basis, ventral margin with 3 simple setae and 2 short submarginal RS; merus 0.5 times as long as ischium, 1.6 times as long as wide, ventral margin with 4 simple setae, 2 short submarginal setae, dorsal distal angle with 1 long RS and 1 short simple seta; carpus 1.3 times as long as ischium, 3.8 times as long as wide, ventral margin with 5 RS, dorsal margin with 2 simple setae, dorsal distal angle with 3 simple setae; propodus weakly curved, 0.3 times as long as ischium, 3.2 times as long wide, ventral margin with 4 RS and 4 short submarginal simple setae, dorsal margin with 3 long simple setae, dorsal distal angle with 3 long simple setae; dactylus 0.8 times as long as propodus smoothly curved, dorsal unguis slight longer than ventral unguis, 2 setae set between ungui. Pereopod 6 similar to pereopod 7, inferodistal angle of basis with 2 prominent acute RS. Pereopod 7 1.3 times longer than pereopod 1; basis 3.8 times as long as greatest width; ischium 0.7 as long as basis, 3.8 times as long as wide, ventral margin with 3 simple setae and 2 short submarginal setae; merus 0.6 times as long as ischium, 3.8 times as long as wide, ventral margin with 6 simple setae, dorsal distal angle with 2 long RS and 1 simple seta; carpus 1.2 times as long as ischium, 5.4 times as long as wide, ventral margin with 6 RS, dorsal margin with 1 RS, dorsal distal angle with 1 RS, 1 plumose and 1 long simple setae; propodus 1.5 times as long as ischium, 7.8 times as long as wide, ventral margin with 5 RS, dorsal margin with (from proximal to distal) 1 short simple setae, group of 3 long simple setae, 1 short simple setae, and distal angle with 2 slender and 1 plumose setae.

Pleopod 1 3.9 times as long as greatest width, widest at basal one­third, lateral margin narrowing abruptly at that point, tapering smoothly to bi­lobed apex; lateral margin basally with 7–9 sort simple setae, distally with 4 long simple setae, distal 2 more than twice as long as proximal 2; lateral lobe with 4–6 short simple setae, mesial lobe with 5 widelyspaced long simple marginal setae, ventral surfaces with scale­setae; stylet guide simple, weakly defined lateral sub­marginal groove. Pleopod 2 basis 2.6 times as long as greatest width, later margin with middle half strongly convex, with continuous close­set simple setae, distal one­third concave, with widely­spaced feebly plumose setae, apex with 6 long simple and plumose setae; endopod (stylet) with long, coiled extension; exopod with bilobed apex. Pleopod 3 exopod and endopod distal margins each with 6 plumose setae; exopod lateral margin with continuous fringe of scale­setae. Pleopod 4 exopod about half as long as endopod, apically acute. Pleopod 5 slightly (0.9) shorter than pleopod 4, lateral margin with basal lobe, mid­lateral margin with small lobe.

Uropods not known, missing from all specimens.

Female: Similar to male with the exception of sexual characters and larger body size. Pleopod 2 about as long (1.13) as wide, lateral margins strongly convex, posteriorly with distinct apical lobe; margins fringed with long setae along distal two­thirds of margins; distal setae more widely spaced.

Colour: The male with dark brown chromatophores as figured, those on the pleotelson pale orange in colour in the preserved specimen; with small chromatophores on the lateral margin of pereonites. Pereopods of both sexes with prominent and separate chromatophores giving a distinctive irregular banded appearance. Chromatophores not apparent on the pleotelson of the female.

Remarks: Mexicope sushara sp. nov. is readily identified by the short rostral point, stalked eyes, and prominent pre­ocular spines or lateral projections. These characters also serve to distinguish the species from all other Acanthaspidiidae .

Associated isopod fauna: Several samples (13 in all), all from bryozoans, were examined. The most abundant species were a species of Schottea Serov & Wilson, 1999 (Pseudojaniridae) and a species of Iathrippa Bovallius, 1866 [see Wilson & Wägele (1994) for a recent account] ( Janiridae ). There was a single specimen of one other isopod, provisionally assigned to Paramunnidae .

Etymology: The epithet combines the Latin words sus (pig) and hara (pen, coop or sty) and alludes to the ability of these preserved specimens to collect adherent detritus; referring to the character ‘Pigpen’ in the famous comic strip Peanuts, who gathered dirt no matter what.

Figures

FIGURE 1. Mexicope sushara sp. nov. Holotype, except F – H, paratype (NIWA 3299). A, dorsal view; B, pleotelson, lateral margin; C, pleotelson, ventral view, post dissection; D, anal aperture; E, pleotelson, ventral view, pre­dissection; F, head; G, lateral view; H, pleotelson, ventral view, female paratype; I, setae from mid­dorsum, pereonite 2; J, posterior lobe, lateral margin, pereonite 2. Scale line = 0. 5 mm.

FIGURE 2. Mexicope sushara sp. nov. Holotype, except B, paratype (NIWA 3299). A, maxilliped; B, maxilliped endite, mesial margin, from dorsal view; C, maxilliped endite, distal margin; D, antennule; E, antenna, peduncle articles 2 – 4; F, antenna, peduncle articles 5, 6 and flagellum.

FIGURE 3. Mexicope sushara sp. nov. Holotype. A, right mandible; B, left mandible; C, maxilla (entire); D, maxilla, distal detail; E, maxillule (entire); F, maxillule, distal detail.

FIGURE 4. Mexicope sushara sp. nov. Holotype. A – D, pereopods 1, 2, 6 and 7 respectively; E, pereopod 7 dactylus.

FIGURE 5. Mexicope sushara sp. nov. Holotype. A – D, pleopods 1 – 5 respectively.