Aega trulla, Bruce, 2004

Bruce, Niel L., 2004, Reassessment of the isopod crustacean Aega deshaysiana (Milne Edwards, 1840) (Cymothoida: Aegidae): a worldwide complex of 21 species, Zoological Journal of the Linnean Society 142 (2), pp. 135-232 : 203-205

AEGA TRULLA SP. NOV. ( FIGS 45–48 , 64 )

? Aega antillensis – Hale, 1925: 176 (part).

Aega deshaysiana – Hale, 1940: 205 (part).

Material examined

Holotype: ♀ (non-ovig. 49 mm [mouthparts on SEM stub]), Coral Sea , east of Townsville, Queensland, Australia, 19∞00.65¢S, 150∞39.20¢E, 24.xi.1985, stn 35, 752 m, coll. CSIRO FRV Soela ( NTM Cr013497).

Paratypes: ♀ (non-ovig. 39 mm [dissected]), off Marion Reef , north-east of Mackay, Queensland, Australia, c. 650 m, coll. QFS ( QM W14371) . ♀ (non-ovig. 53 mm), Ontong Java Atoll (c. 8∞S, 159∞E), Solomon Islands, 22.vi.1918, coll. H. Hogben (AM P9267 [ Hale 1940]) .

Description

Body 2.3 times as long as greatest width, dorsal surfaces smooth (finely punctate), widest at pereonite 5, lateral margins weakly ovate. Rostral point projecting anteriorly, not ventrally folded. Eyes large, medially united, anterior clear field 8% length of head, posterior clear field 21% length of head; each eye made up of ~32 transverse rows of ommatidia, each row with ~23 ommatidia; eye colour pale brown. Pereonite 1 and coxae 2–3 each with posteroventral angle rounded; coxae 5–7 with entire oblique carina. Pleon with pleonite 1 visible in dorsal view; pleonite 4 with posterolateral margins extending clearly beyond posterior margin of pleonite 5; pleonite 5 with posterolateral angles free, not overlapped by lateral margins of pleonite 4. Pleotelson 1.1 times as long as anterior width, dorsal surface without longitudinal carina; lateral margins sinuate, smooth, posterior margin with elongate medial point, with 15–17 RS.

Antennule peduncle articles 1 and 2 flattened, article 2 without anterodistal lobe; articles 3 and 4 0.6 times as long as combined lengths of articles 1 and 2, article 3 3.0¥ LW; flagellum with 10 articles, extending to mid-point of eye. Antenna peduncle article 2 inferior surface without distinct longitudinal suture; article 4 2.2¥ LW, 1.4 times as long as combined lengths of articles 1–3, with deep longitudinal groove, inferior margin with 1 plumose seta, and 0 short simple setae; article 5 not markedly wider or flatter than article 4, 1.2¥ L article 4, 2.5¥ LW (inferior margin scalloped), inferior margin with 3 plumose setae, anterodistal angle with cluster of 3 short simple setae; flagellum with 20 articles, extending to posterior of pereonite 1.

Frontal lamina flat, as wide as long, oval, anterior margin with median indentation (minute), without small median point, posterior margin not abutting clypeus.

Mandible molar process absent; palp article 2 with 11 distolateral setae (and 3 submarginal setae), palp article 3 with 26 setae. Maxillule with 8 terminal RS (large, falcate). Maxilla medial lobe with 4 RS (2 hooked, 2 straight); lateral lobe with 4 RS (hooked). Maxilliped endite with 1 apical seta; palp article 2 with 3 RS (acute); article 3 with 4 recurved RS (weakly recurved; 3 marginal, hooked plus 1 mesial straight); article 4 with 5 hooked RS (4 large and 1 small); article 5 partly fused to article 4, with 5 RS (basally bent then straight).

Pereopod 1 basis 1.9 times as long as greatest width; ischium 0.6¥ L basis, inferior margin with 0 RS, superior distal margin with 2 RS; merus inferior margin with 5 RS, set as single (indistinct) row, superior distal angle with 2 RS; carpus 0.7¥ L merus, inferior margin with 0 RS; propodus 1.2 times as long as proximal width, inferior margin with 0 RS, propodal palm with distal blade (as wide as full length of palm, distally convex), dactylus smoothly curved, 2.0¥ L propodus. P2 ischium inferior margin with 2 RS, superior distal margin with 2 RS; merus inferior margin with 7 RS, set as single row, superior distal margin with 2 acute RS; carpus similar in size to that of P1, inferodistal angle with 1 RS, propodus without large club-shaped distal RS. P3 similar to P2 (but ischium inferior margin with 5 RS; carpus proportionally longer); propodus without large club-shaped distal RS. P6 similar to P7 (but more robust). P7 basis 3.4 times as long as greatest width, inferior margin with 8 palmate setae (most missing); ischium 0.5¥ L basis, inferior margin with 10 RS (set as 1, 2 and 6), superior distal angle with 4 RS, inferior distal angle with 5 RS; merus 0.9¥ L ischium, 2.3¥ LW, inferior margin with 8 RS (loosely set as 4 and 4), superior distal angle with 5 RS, inferior distal angle with 5 RS; carpus 0.9¥ L ischium, 2.8¥ LW, inferior margin with 5 RS (set as 2 and 3), superior distal angle with 6 RS, inferior distal angle with 6 RS; propodus 0.6¥ L ischium, 3.6¥ LW, inferior margin with 4 RS (set as 2 and 2), superior distal angle with 3 slen- der setae (2 simple, 1 palmate), inferior distal angle with 4 RS.

Pleopod 1 exopod 2.2¥ LW, distally narrowly rounded with strongly oblique medial margin, lateral margin distally concave, medial margin strongly convex, with PMS from base; endopod 2.5¥ LW, distally subtruncate, lateral margin sinuate (widest distally), with PMS from on distal margin only, medial margin with PMS from distal half; peduncle 1.6¥ WL, medial margin with 12 coupling hooks. Exopods of pleopods 1–5 each with distolateral margin not deeply serrate; endopods of pleopods 3–5 each with mediodistal point; pleopods 2–5 peduncle distolateral margin without prominent acute RS.

Uropod peduncle ventrolateral margin with 2 RS, posterior lobe about 0.6¥ L endopod. Uropod rami not coplanar, exopod at angle of about 135∞ to endopod, rami not extending beyond pleotelson, marginal setae in single tier, apices narrowly rounded and broadly rounded (endopod narrowly rounded or subtruncate, exopod broadly rounded). Endopod apically not bifid, lateral margin proximally convex, distally straight, with prominent excision positioned about three-quarters along ramus, proximal lateral margin with 2 RS, distal lateral margin with 4 RS, medial margin weakly convex, with 5 RS. Exopod extending to end of endopod, 2.2 times as long as greatest width, apically not bifid; lateral margin convex, with 14 RS; medial margin convex, with 6 RS.

Figures

Figure 45. Aega trulla sp. nov. A–F, holotype, remainder paratype QM W14371. A, dorsal view. B, lateral view. C, head, dorsal view. D, frons. E, pleotelson posterior margin, dorsal view. F, pleotelson posterior margin, dorsal view. G, antennule. H, antenna peduncle. I, antenna peduncle, articles 1–3.

Figure 46. Aega trulla sp. nov. Paratype QM W14371. A, mandible. B, mandible palp article 3. C, maxillule apex. D, maxillule. E, maxilliped. F, maxilliped palp article 5. G, maxilliped palp articles 2–5. H, maxilla, apex detail. I, maxilla.

Figure 47. Aega trulla sp. nov. Paratype QM W14371. A–E, pereopods 1–3, 6 and 7, respectively. F, pereopod 2, mesial surface, propodal blade.

Figure 48. Aega trulla sp. nov. Paratype QM W14371. A, pleopod 1. B, pleopod 2. C, uropod. D, uropod exopod, ventral view. E, uropod endopod apex. F, uropod exopod apex.

Figure 64. Distributions of: Aega musorstom sp. nov. (•), A. trulla sp. nov. (*), A. umpara sp. nov. (O) and A. warna sp. nov. (-).