Agononida auscerta, Poore, Gary C. B. & Andreakis, Nikos, 2012

Poore, Gary C. B. & Andreakis, Nikos, 2012, The Agononida incerta species complex unravelled (Crustacea: Decapoda: Anomura: Munididae), Zootaxa 3492, pp. 1-29 : 16-18

Agononida auscerta n. sp.

( Figs 2 F, G, 9)

Agononida sp. aff. incerta .—Poore et al. 2008: 18 (part).

Material examined. Holotype. AUSTRALIA. Western Australia, Imperieuse L23 west transect, 17°31S 118° 51.1°E, 406– 405 m, 16.06.2007, beam trawl (stn SS05/2007/064), NMV J55995 (ovigerous female, cl 24.3 mm).

Paratypes. AUSTRALIA. Western Australia (all collected by FRV Southern Surveyor, 2005–2007). Adele L28 transect, 14°03.68ʹS 122°37ʹE, 394–400 m (stn SS05/2007/166), NMV J56126 (male, cl 8 mm). Leveque L27 transect, 14°51.2ʹS 121°25.8ʹE, 403– 396 m (stn SS05/2007/144), NMV J56026 (5 males, cl 19–23 mm; 4 females, cl 18–25 mm). Broome L25 transect, 16°36.3ʹS 120°34.4.5ʹE, 407–414 m (stn SS05/2007/120), NMV J56417 (1 male, cl 10 mm; 3 juvenile females cl 7–12 mm). Imperieuse L23 transect, 17°21.5ʹS 118°57.3ʹE, 437–446 m (stn SS05/2007/056), NMV J56110 (2 males, cl 5, 11 mm; female, cl 11 mm). Imperieuse L23 transect, 17°31ʹS 118°51.1ʹE, 406– 405 m (stn SS05/2007/064), NMV J55992 (6 juveniles). Imperieuse L23 transect, 17°31.7ʹS 118°50.6ʹE, 407– 403 m (stn SS05/2007/057), NMV J56101 (3 males, cl 18–21 mm; 3 females, cl 19–23 mm). Hedland L22 transect, 18°34.2ʹS 117°27.8ʹE, 405– 401 m (stn SS05/2007/052), NMV J55275 (3 males, cl 19–22 mm); NMV J62124 (male, cl 22 mm). Hedland L22 transect, 18°34.2ʹS 117°27.4ʹE, 407– 404 m (stn SS05/2007/ 049), NMV J56112 (3 males, cl 17–20 mm; female, cl 8 mm). Karratha L21 transect, 18°46.4ʹS 116°54.7ʹE, 404– 400 m (stn SS05/2007/036), NMV J56106 (female, cl 8 mm). Off Barrow Island, 21°00.4ʹS 114°22.8ʹE, 399–408 m (stn SS10/2005/172), NMV J55032 [now in MNHN] (3 males, cl 21 mm); NMV J60648 (male, cl 21 mm). Off Ningaloo North, 21°58.2ʹS 113°47.4ʹE, 373–382 m (stn SS10/2005/165), NMV J55022 (male, cl 22 mm).

Diagnosis. Telson anterolateral margin almost straight over anterior three-quarters, posterior quarter separated by shallow hiatus. Pereopodal 2–4 dactyli 8–9 times as long as greatest basal width; robust setae on dactylus of pereopod 2 number 2–6 (median 4; rarely 8), of pereopod 3, 1–4 (median 2) and of pereopod 4, 1–2 (rarely 3). Pereopod 4 merus without spines proximally on upper face.

Descriptions. Ovigerous female. Based on NMV J55995 , cl 24.3 mm. Carapace 0.9 times as long as greatest width. Frontal margin inclined posteriorly at 11° from midline. Rostrum spiniform, 0.47 length of carapace (both measured from base of supraocular spines); supraocular spine 0.6 length of rostrum (both measured from base of rostrum). Thoracic sternite 3 0.49 width of sternite 4; midlength of sternal plastron (sternites 4–7) 0.6 width of sternite 7. Telson greatest width 1.9 times midlength; anterolateral margin almost straight over anterior threequarters, posterior quarter separated by shallow hiatus; posterior part with expanded lateral margin then tapering to posterior transverse suture; lateral margin evenly convex.

Eyes with maximum corneal diameter 1.1 basal width of supraocular spines. Maxilliped 3 ischium 0.7 times as long as merus.

Pereopod 1 (cheliped) of typical adult form, covered with flat squamae fringed with short setae; 3.5 times as long as carapace, merus 1.3 times as long as carapace, carpus 0.54 times as long as merus, propodus 1.3 times as long as merus, fingers 0.43 times as long as total propodus length. Merus with 1+7–8 spines along upper margin, 3–4 spines along mesial face, 10–12 spines along lateral face, with distal spine and 1–3 spine-like squamae on lower margin; carpus with 1+2 spines on upper margin, 2–3 spines on mesial face, 0–1 spines on lateral face; propodus oval in cross-section, spines with marginal spines, with 3–4 spines on upper margin, with 1+1–3 spines along mesial face, with 1+1–2 spine on lateral face near base of dactylus, with 1–3 oblique spines along lower margin, without spines on lower lateral face; dactylus cutting edge with ridge of c. 20 uneven teeth, few more prominent than others.

Minor pereopod 1 not differentiated (except in numbers of spines).

Pereopod 2 3.4 times carapace length, merus 1.3 times carapace length, 8.5 times a long as greatest width, carpus 0.25 times as long as merus, propodus 0.7 times as long as merus, dactylus 0.7 times as long as propodus; merus with 1+11 spines along extensor margin, with 1+7 spines along flexor margin; carpus with 1+0 spines along extensor margin; dactylus evenly curved over distal two-thirds, 9 times as long as greatest basal width, with row of 4 robust setae distal to heel of flexor margin.

Pereopod 3 3.5 times carapace length, merus 1.3 times carapace length, 8.5 times a long as greatest width, carpus 0.3 times as long as merus, propodus 0.7 times as long as merus, dactylus 0.6 times as long as propodus; merus with 1+15 spines along extensor margin, with 1+9 spines along flexor margin; carpus with 1+1 spines along extensor margin; dactylus evenly curved over distal two-thirds, 8.1 times as long as greatest basal width, dactylus with 2 robust setae distal to heel of flexor margin.

Pereopod 4 3.5 times carapace length, merus 1.3 times carapace length, 7.1 times a long as greatest width, carpus 0.3 times as long as merus, propodus 0.7 times as long as merus, dactylus 0.5 times as long as propodus; merus with 1+11 spines along extensor margin, with 1+8 spines along flexor margin; carpus with 1+1 spines along extensor margin; dactylus of similar curvature to dactyli 2 and 3, distally less setose, 8.6 times as long as greatest basal width, dactylus with 1 robust seta(e) distal to heel of flexor margin.

Male. Based on NMV J62124 , cl 22 mm. Telson anterolateral margin almost straight over anterior half, posterior half with irregular anterior margin and convex posterior lobe; lateral margin convex, narrower posteriorly than anteriorly.

Variation. No supermale is known. Males and ovigerous females of similar sizes differ only slightly, the anterolateral margin of the telson being slightly more irregular in males than females; the chelipeds do not differ between sexes. The numbers of spines on the margins of pereopodal meri may be one or two larger or smaller than the figures given in the descriptions and are not consistent from left to right side. The numbers of robust setae distal to the heel on the flexor margin of the dactyli of pereopods 2–4 vary considerably: pereopod 2, 2–6 (median 4; rarely 8); pereopod 3, 1–4 (median 2); pereopod 4, 1–2 (rarely 3).

Distribution. Western Australia, 14°S–22°S; 373–446 m (the species was not taken at stations targeting the 200 m, 800 m or deeper contours).

Etymology. auscerta , a combination from Australia and incerta .

Remarks. Agononida auscerta is morphologically similar to A. incerta , differing in its characteristic telson, more elongate dactyli of pereopods 2–4, and in the numbers of robust setae along their flexor margins. The anterolateral margin on the telson has only a slight indentation in the male (almost none in the female), the anterior three-quarters being only slightly concave if at all and the posterior quarter barely convex ( A. incerta always has a clear notch separating these two sections). The pereopodal dactyli are narrower than those of all other species. The numbers of robust setae on pereopodal dactyli are fewer, usually 2–6 on pereopod 2 (12–30, median 17, in A. incerta ) and 1–4 on pereopod 3 (2–10, median 6, in A. incerta ). Both have 1–3 on pereopod 4. Agononida auscerta differs from A. indocerta with which it also co-occurs in WA in having the telson anterolateral margin almost straight over anterior three-quarters (concave and smooth over anterior 70% in A. indocerta ) and lacking the prominent posterior lobe with a crenellate margin, and in having usually 2–6 robust setae on the dactylus of pereopod 2 (25–50,median about 35 in A. indocerta ), and 1–4 on pereopod 3 (6–31, median about 17 in A. indocerta ).

Our mitochondrial phylogenetic reconstruction placed Agononida auscerta as sister taxon to A. rubrizonata . The latter species shows a wider geographical distribution, encompassing the former, and can be distinguished from the former on the basis of telson shape, even as females.

Figures

FIGURE 2. Telsons of species of the Agononida incerta complex, with details of the anterolateral margin at twice scale. Scale bar = 10 mm. Agononida incerta: A, male, cl 32 mm, Western Australia, NMV J 56025. B, ovigerous female, cl 24 mm, Western Australia, NMV J 55021. C, supermale, cl 38 mm, Philippines, ZMUC CRU 11555. Agononida africerta: D, male, cl 15.1 mm, MNHN IU- 2008 - 10437. E, female, cl 13.8 mm, MNHN IU- 2008 - 10438. Agononida auscerta: F, male, cl 22 mm, NMV J 62124. G, ovigerous female, cl 24.3 mm, NMV J 55995. Agononida indocerta: H, supermale, cl 30.3 mm, NMV J 62081. I, male, cl 27 mm, NMV J 57295. J, ovigerous female, cl 25 mm, NMV J 57295. Agononida norfocerta: K, male, cl 30.7 mm, MNHN IU- 2011 - 592. L, female, cl 27 mm, NMV J 62814. Agononida rubrizonata: M, male, cl 28.2 mm, Western Australia, NMV J 57292. N, ovigerous female, Western Australia, cl 25 mm, NMV J 57292.