Agononida incerta ( Henderson, 1888 )

Poore, Gary C. B. & Andreakis, Nikos, 2012, The Agononida incerta species complex unravelled (Crustacea: Decapoda: Anomura: Munididae), Zootaxa 3492, pp. 1-29 : 7-10

Agononida incerta ( Henderson, 1888)

( Figs 2 A–C, 3A, B, 4–7)

Munida incerta Henderson, 1888: 130 , pl. 13, figs 4, 4a. Agononida incerta .—Baba et al. 2009: 76–78, fig. 63.

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

Material examined. Holotype. Celebes Sea, Philippines, off Sibago Island (off Zamboanga), 06°47´N, 122°28´E, 458 m, BMNH 1888:33 (female without chelipeds, pereopods missing or fragmented and unattached, cl 15.8 mm).

Other material. TAIWAN. Su-ao fishing port, 10.03.2005, NTOU M01563 (3 juveniles, cl 9–13 mm); 0 5.12.1991, NTOU M01564 (2 males, cl 12, 18 mm). Taiwan, 22°11.4’N, 120°22.58ʹE, 280–452 m, 23.11.2001 (stn CD140), NTOU M01565 (3 ovigerous females, 20–23 mm; 2 males, cl 18, 11 mm).

PHILIPPINES, Celebes Sea, 25 mi E by S of Zamboanga, 06°42’N 122°19ʹE, 366– 293 m, 0 3.05.1914 (Th. Mortensen colln stn KB555), ZMUC CRU- 11555 (4 females, cl 11–21 mm; 2 males, cl 22, 38 mm). 25 mi E of Zamboanga, 06°54’N 122°25ʹE, 460 m, 0 4.05.1914 (Th. Mortensen stn KB576), ZMUC CRU- 11576 (male, cl 11 mm).

Philippines Sea, E of Luzon, Philippines, 15°59.45’N 121°50.68ʹE, 422–431 m, 20.05.2007 (stn CP2658), NTOU M01566 (2 females, cl 7.5, 9.5 mm; 2 males cl 7, 11 mm).

AUSTRALIA. Western Australia (all collected by FRV Southern Surveyor, 2005–2007). Ashmore L30 transect, 12°31.7ʹS 123°25.6ʹE, 401–404 m (stn SS05/2007/192), NMV J56025 (male, cl 32 mm). Ashmore L30 transect, 12°36.1ʹS 123°25.5ʹE, 419– 403 m (stn SS05/2007/198), NMV J56111 (male, cl 26 mm). Off Barrow Island transect, 21°00.38ʹS 114°22.86ʹE, 399–411 m (stn SS10/2005/171), NMV J55054 (2 females, cl 9, 20 mm). Off Barrow Island, 21°00.40ʹS 114°22.9ʹE, 399–408 m (stn SS10/2005/172), NMV J59657 (2 males, cl 18. 18 mm). Off Ningaloo North, 21°58.2ʹS 113°47.5ʹE, 356– 324 m (stn SS10/2005/157), NMV J55025 (males, cl 29 mm). Off Ningaloo North, 21°58.2ʹS 113°47.4ʹE, 373–382 m (stn SS10/2005/165), NMV J59659 (male, cl 12 mm); NMV J59658 (male, cl 12 mm). Off Ningaloo South, 22°04.31ʹS 113°45.3ʹE, 399– 387 m (stn SS10/2005/ 151), NMV J55020 (male; female, cl 11 mm), NMV J60835 (male, cl 25 mm). Off Point Cloates, 22°50.8ʹS 113°20.2ʹE, 420–430 m (stn SS10/2005/137), NMV J55053 (2 males, cl 18, 19 mm). Off Red Bluff, 23°59.1ʹS 112°32.7ʹE, 398–402 m (stn SS10/2005/128), NMV J55021 (ovigerous female, cl 24 mm).

Diagnosis. Telson anterolateral margin quasi-3-lobed, middle lobe largest, with sharp edge, deflected dorsally, separated from weak anterior lobe by shallow concavity and from more rounded thicker posterior lobe by deep notch, exaggerated in males, finely crenellate over posterior two-thirds in larger individuals. Pereopodal 2–4 dactyli 5.1–6.6 times as long as greatest basal width; robust setae on dactylus of pereopod 2 number 12–30 (median 17, rarely 4), of pereopod 3, 2–10 (median 6, rarely 1–17), and of pereopod 4, 1–3 (rarely 6). Pereopod 4 merus without spines proximally on upper face.

Descriptions. Adult male. Based on NMV J56025 (cl 32 mm). Carapace 0.9 times as long as greatest width. Gastric region with pair of small lateral epigastric spines. Frontal margin inclined posteriorly at 12° from midline. Rostrum spiniform, 0.43 length of carapace (both measured from base of supraocular spines); supraocular spine 0.64 length of rostrum (both measured from base of rostrum). Thoracic sternite 3 0.43 width of sternite 4; midlength of sternal plastron (sternites 4–7) 0.6 width of sternite 7. Telson greatest width twice midlength; anterolateral margin quasi-3-lobed, middle lobe largest, with sharp edge, deflected dorsally, separated from weak anterior lobe by shallow concavity and from more rounded thicker posterior lobe by deep notch, finely crenellate over posterior two-thirds; lateral margin evenly convex.

Eyes with maximum corneal diameter 1.1 basal width of supraocular spines. Maxilliped 3 ischium 0.6 times as long as merus.

Pereopod 1 (cheliped) of typical adult form, covered with flat squamae fringed with short setae; 3.3 times as long as carapace, merus 0.9 times as long as carapace, carpus 0.78 times as long as merus, propodus 1.8 times as long as merus, fingers 0.5 times as long as total propodus length. Pereopod 1 (cheliped) merus with 1+9 spines along upper margin, 4–5 spines along mesial face, 15 spines along lateral face, with distal spine only on lower margin; carpus with 1+3 spines on upper margin, 3 spines on mesial face, 1 spines on lateral face; propodus oval in cross-section, spines with marginal spines, with 3–4 spines on upper margin, with 1+0–1 spines along mesial face, with 1+0 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. 50 uneven teeth, few more prominent than others.

Minor pereopod 1 not differentiated.

Pereopod 2 3.5 times carapace length, merus 1.5 times carapace length, 9.4 times a long as greatest width, carpus 0.25 times as long as merus, propodus 0.6 times as long as merus, dactylus 0.5 times as long as propodus; merus with 1+12 spines along extensor margin, with 1+6 spines along flexor margin; carpus with 1+1 spines along extensor margin; dactylus evenly curved over distal two-thirds, 6.6 times as long as greatest basal width, with row of 18 robust setae distal to heel of flexor margin.

Pereopod 3 3.5 times carapace length, merus 1.5 times carapace length, 8.3 times a long as greatest width, carpus 0.3 times as long as merus, propodus 0.6 times as long as merus, dactylus 0.5 times as long as propodus; merus with 1+15 spines along extensor margin, with 1+6 spines along flexor margin; carpus with 1+2 spines along extensor margin; dactylus evenly curved over distal two-thirds, 6.6 times as long as greatest basal width, with row of 5 robust setae distal to heel of flexor margin.

Pereopod 4 3.3 times carapace length, merus 1.3 times carapace length, 7.2 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+13 spines along extensor margin, with 1+6 spines along flexor margin; carpus with 1+1 spines along extensor margin; dactylus more gently curved than dactyli 2 or 3, distally less setose, 6.5 times as long as greatest basal width, with 5 robust seta(e) distal to heel of flexor margin.

Supermale. Based on ZMUC CRU-11555, cl 38 mm. Carapace as long as greatest width. Rostrum spiniform, 0.4 length of carapace (both measured from base of supraocular spines). Telson anterolateral margin with shallow concavity near anterior curvature of anterior section, almost straight beyond this point, a second shallow concavity 70% along anterolateral margin, separating the anterior section from rounded, lobed, slightly crenellate posterior section; lateral margin almost straight, more curved proximally and distally.

Pereopod 1 (cheliped) of grossly expanded supermale form, slightly asymmetrical, covered with elevated squamae fringed with short setae; 3.7 times as long as carapace, merus 1.1 times as long as carapace, carpus 0.64 times as long as merus, propodus 1.5 times as long as merus. Pereopod 1 (cheliped) merus with 1+5 spines along upper margin, 2 spines along mesial face, 10 spines along lateral face; carpus with 1+2 spines on upper margin, 1 spines on mesial face, 0 spines on lateral face; propodus oval in cross-section, with shallow longitudinal grooves mesially and laterally, palm deeper distally, with 3 spines on upper margin, with 1+0 spines along mesial face, with 1+1 spine on lateral face near base of dactylus, without spines along lower margin or on lower lateral face; dactylus cutting edge with 2 proximal blunt teeth and ridge of c. 50 uneven teeth, few more prominent than others.

Minor pereopod 1 only slightly less developed than other, minor differences in spination.

Pereopod 2 3 times carapace length, merus 1.3 times carapace length, 7.1 times a long as greatest width; merus with 1+11 spines along extensor margin, with 1+4 spines along flexor margin; carpus with 1+0 spines along extensor margin; dactylus 5.1 times as long as greatest basal width, with row of 30 robust setae distal to heel of flexor margin.

Pereopod 3 3 times carapace length, merus 1.3 times carapace length, 6.7 times a long as greatest width; merus with 1+11 spines along extensor margin, merus with 1+4 spines along flexor margin; carpus with 1+1 spines along extensor margin; dactylus 5.2 times as long as greatest basal width, with row of 6 robust setae distal to heel of flexor margin.

Pereopod 4 2.8 times carapace length, merus as long as carapace length; merus with 1+8 spines along extensor margin, merus with 1+4 spines along flexor margin; dactylus 5.3 times as long as greatest basal width, with 1 robust seta distal to heel of flexor margin.

Ovigerous female. Based on NMV J55021 (cl 23 mm). Telson anterolateral margin quasi-3-lobed, middle lobe with rounded edge, not deflected dorsally, separated from weak anterior lobe by shallow concavity and from more rounded thicker posterior lobe by broad notch, finely crenellate over posterior third.

Pereopod 1 (cheliped) merus with 1+5–6 spines along upper margin, 5 spines along mesial face, 11 spines along lateral face. Pereopod 1 (cheliped) carpus with 1+2 spines on upper margin, 2 spines on mesial face. Pereopod 1 (cheliped) propodus with 3 spines on upper margin, with 1+1–3 spines along mesial face, with 1+1 spine on lateral face near base of dactylus.

Colour. Based on WA specimen, NMV J55021 ( Figs 3 A, B). Unevenly orange over carapace and abdominal somites 1–4, abdominal somites 5, 6 and telson uncoloured; colour highlighted at the bases of abdominal spines and spines on pereopodal meri; narrow transverse orange bands at the ends of meri, carpi and propodi of pereopods 1–4.

Variation. Agononida incerta displays both allometric and sexual variation. One supermale captured close to the type locality was identified with thickened chelipeds 12% longer than a typical male. The critical specific character, the anterolateral margin of the telson, always displays a clear deep hiatus between the middle and rounded posterior lobes. The middle lobe is not more prominent than the posterior lobe in females and juveniles, while in adult males, it is larger, with a sharp edge deflected dorsally. The deflection is more subdued in supermales.

Besides this variation is some more at random. Some individuals possess only two postcervical spines on one or both sides (rather than three pairs). Some larger specimens from Western Australia have a minute epigastric spine lateral to the pair of major epigastric spines. While the number of mesial spines on the merus of the cheliped is seven or eight on the male described above, 3–5 is more typical. 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, more on larger specimens: pereopod 2, 12–30 (median 17; rarely 4); pereopod 3, 2–10 (median 6, rarely 1–17); pereopod 4, 1–3 (rarely 6).

Distribution. Taiwan, Philippines to southern Western Australia; 22°N–24°S; 280–460 m (in Western Australia the species was not taken at stations targeting the 200 m, 800 m or deeper contours).

Remarks. The holotype is a small incomplete female with what few limbs remain detached ( Figs 4 , 5 ). Three key features, besides the coincidence of the collecting locality, enable the ZMUC material to be confidently identified. Apart from the supermale, the specimens from this collection were fragmented and limbs mixed. The shape of the anterolateral margin of the telson is consistent across all specimens; the proportions of the dactyli of pereopods 3 and 4 are within the range for this species; and the numbers of robust setae on the flexor margins of these articles, 9 and 1 on the holotype, are consistent with pereopods 3 and 4. The four specimens collected by NTOU in the Philippines are all small with more elongate pereopodal dactyli than typical, fewer robust setae on the dactylus of pereopod 2 (4–5) but the strong hiatus along the anterolateral margin of the telson is typical of A. incerta . The material from northwestern Australia could not be distinguished on morphological grounds. A typical male and female from this locality are illustrated.

Agononida incerta is distinguished from other species in the genus by the particularly broad dactyli of pereopods 2–4 in larger specimens, and the high number of robust setae on pereopodal dactyli 2 and 3, up to 30 and 17 respectively (usually around 17 and 6). These numbers are similar to those on A. indocerta and A. africerta , species that differ in several other ways. As with other species it has its own characteristic shape of the anterolateral margin of telson, notably in adult males the large middle lobe with a sharp edge deflected dorsally, separated from weak anterior lobe by shallow concavity and from more rounded thicker posterior lobe by a deep notch. See remarks under Agononida auscerta .

The small holotype has a proportionately longer rostrum and longer telson than the adult male and supermale.

Agononida incerta is genealogically more closely related to A. norfocerta found only in Norfolk Ridge (SW Pacific), than to any other species ( Fig. 1 ).

The photograph ( Fig. 12 A) of a specimen from Nanfang-Ao, Taiwan, and published previously by Baba et al. (2009) illustrates narrower pereopods than the large supermale from the same region but is similar to others of the same size.

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.

FIGURE 3. Colour photographs of living animals. A, Agononida incerta, Nanfang-ao, Taiwan, T. - Y. Chan (from Baba et al., 2009). B, A. incerta, NMV J 55021, Karen Gowlett-Holmes. C, A. africerta, MNHN IU- 2008 - 10192, T. - Y. Chan. D, A. indocerta, Western Australia, D. Evans (from Jones & Morgan, 2002). E, A. rubrizonata, paratype, Taiwan, T. - Y. Chan. F, A. rubrizonata, Western Australia, NMV J 55029, Karen Gowlett-Holmes.

FIGURE 4. Agononida incerta (Henderson, 1888) Holotype, juvenile female. A, dorsal view; B, telson. Scale bars = 10 mm.

FIGURE 5. Agononida incerta (Henderson, 1888) Holotype, juvenile female. A, telson and uropod; B, sternal shield; C, maxilliped 3; C, left antennule and antenna, ventral view; E, free dactylus (probably of pereopod 2, with 9 robust setae); F, carpus – dactylus, pereopod 4 (with 1 robust seta). Scale bar = 5 mm.

FIGURE 12. Agononida rubrizonata Baba & Macpherson, 2009. Male, NMV J 57292. A, habitus; B, telson; C, dactyli of pereopods 2 – 4 with detail of robust setae at greater magnification. Female, NMV J 57292. D, telson. Scale bar = 10 mm.

FIGURE 1. A, model-constrained maximum-likelihood phylogeny inferred from the partial COI sequences. Heuristic searches retained one tree (- ln = 2264.2673). Numbers on nodes, indicate bootstrap support for that node. B, geographical distribution of the specimens analysed. Coloured dots correspond with the samples analysed for COI and the dotted lines to the distributions of the only widespread species.