Allogalathea longimana, Cabezas & Macpherson & Machordom, 2011

Cabezas, Patricia, Macpherson, Enrique & Machordom, Annie, 2011, Allogalathea (Decapoda: Galatheidae): a monospecific genus of squat lobster?, Zoological Journal of the Linnean Society 162 (2), pp. 245-270 : 261-262

Allogalathea longimana sp. nov. ( Figs 5 , 6D )

Galathea elegans Haswell, 1882: 163 ; Grant & McCulloch, 1906: 50, plate 4, figures 6 and 6a.

Allogalathea elegans Miyake, 1982: 149 , plate 50, colour figure 5.

Material examined: Philippines. Musorstom 3. Stn CP 97, 14°01′N, 120°19′E, 1 June 1985, depth 189– 194 m: one M 6.7 mm (MNHN-Ga7430, Allo44); Stn CP 107, 14°02′N, 120°28′E, 2 June 1985, depth 111– 115 m: one M 3.8 mm (MNHN-Ga7431, Allo46), one ovig. F 6.5 mm (MNHN-Ga7432, Allo38); Stn CP 124, 12°03′N, 121°35′E, 4 June 1985, depth 120–123 m: two M 6.6–7.2 mm, two ovig. F 6.3–7.5 mm (MNHN- Ga7433 and MNHN-Ga7434, Allo45) .

Types: The ovigerous female of 6.5 mm postorbital carapace length from the Philippines (Musorstom 3, Stn CP 107, MNHN-Ga7432) has been selected as the holotype . The other specimens are paratypes.

Etymology: From the Latin longus (long) and manus (hand), referring to the long cheliped (P1) and P1 palm, a character that separates this species from the other three species in this genus.

Description: Carapace, exclusive of rostrum, as long as broad; dorsal surface nearly horizontal from anterior to posterior, and cervical groove very shallow. Gastric region with five or six uninterrupted ridges and two or three interrupted ridges, usually without scales between them, anterior first and third ridges medially convex anteriorly; mid-transverse ridge uninterrupted, extending laterally to sixth marginal spines, preceded by very shallow cervical groove, followed by between six and nine transverse ridges, mostly interrupted. Lateral margins with between eight and ten spines: two spines in front of, and between six and eight spines behind, indistinct anterior cervical groove; first anterolateral, welldeveloped, slightly posterior to level of lateral limit of orbit; second smaller than first, equidistant between anterolateral spine and anterior cervical groove; three spines on anterior branchial region, and between three and five spines on posterior branchial margin, decreasing in size posteriorly. Rostrum moderately long, with between eight and ten small lateral teeth, 1.8 times longer than broad, length 0.7 times that of carapace, dorsal surface nearly horizontal in lateral view, with small setiferous ridges ( Fig. 5A ).

Pterygostomian flap with some setigerous ridges, anterior margin ending in small spine.

Sternal plastron 0.8 times as long as broad, lateral limits divergent posteriorly. Sternite 3 twice as broad as long, anterior margin with small median notch. Sternite 4 2.8 times longer and 2.8 times broader than preceding sternite, 0.5 times as long as broad; sternites 4 and 5 with a few transverse ridges bearing short setae ( Fig. 5B ).

Abdominal somites 2–4 each with four or five uninterrupted transverse ridges on tergite, with or without scales in between; somite 5 with 2 uninterrupted ridges, somite 6 with 2 interrupted ridges and some scales.

Eyestalk (other than cornea) with short fine setae on dorsal anterior extension; cornea moderately dilated.

Article 1 of antennal peduncle with distomesial spine reaching midlength of article 2. Article 2 with distolateral spine clearly longer than distomesial, nearly reaching end of article 3. Article 3 with small, distinct distomesial spine. Article 4 unarmed ( Fig. 5C ).

Mxp3 ischium with well-developed spine on flexor distal margin; extensor margin unarmed; crista dentata with 19–23 denticles. Merus slightly longer than ischium, with two or three strong spines of subequal size on flexor margin, proximal one located at midlength, distal one at terminal end; extensor margin unarmed, or with two or three small spines ( Fig. 5D ).

P1 squamous, 3.9–4.0 times carapace length, subcylindrical, lateral and mesial margins straight in adult specimens, most dorsal squamae unarmed or with one or two small spinules and long setae. Merus 1.1–1.3 times length of carapace, 1.3–1.6 times as long as carpus, with row of a few spines along mesial and distodorsal margins. Carpus 0.6–0.7 times length of palm, 3.8–4.0 times longer than broad, lateral and mesial margins subparallel, mesial and distodorsal margins with row of few spines. Palm 5.0–6.5 times longer than broad, dorsal surface without spinules; lateral and mesial margins subparallel, lacking spines. Fingers 0.4 times as long as palm, distally crossing when closed; opposable margins nearly straight; mesial margin of movable finger with two or three subterminal spines ( Fig. 5E ).

P2–P4 squamous, slender, somewhat compressed, striae with long setae. P2 length 1.6–1.7 times carapace length. Meri successively shorter posteriorly (P3 merus 0.9 times length of P2 merus, P4 merus 0.8 times length of P3 merus); P2 merus 0.6–0.8 times carapace length, 3.5–4.0 times as long as broad, 1.3– 1.5 times longer than P2 propodus. Dorsal margins of meri with distal row of small proximally diminishing spines on P2 and P3, unarmed on P4 except distal spine; ventrolateral margins with strong terminal spine. Carpi with some dorsal spines; flexor distal margins with very small spine. Propodi slightly shorter on P4 than on P2 and P3, 4.0 times as long as broad on P2 and P3; extensor margin unarmed; flexor margin with between six and eight slender movable spines. Dactyli subequal in length, half length of propodi, ending in a curved, strong, sharp spine; flexor margin with prominent triangular terminal tooth preceded by five or six obsolescent teeth, each with seta-like movable spine ( Fig. 5F–H ).

Epipods present on P1.

Colour: Body with alternating longitudinal darkbrown, white, or yellow stripes (pattern 4 of Baba, 1979). The middle stripe is always dark brown. P1–P4 brownish or yellowish.

Remarks: The species can be easily distinguished from the other three species of the genus according to the length of P1. The chelipeds (P1) are about four times the length of the carapace in A. longimana sp. nov., with the palm about twice the finger length. In the other species, the length P1 is always less than three times the carapace length, with the palm as long as or slightly longer than the fingers.

Distribution and habitat: Japan, the Philippines, and Queensland, Australia, between a depth of 36 and 194 m. Habitat unknown.

Figures

Figure 5. Allogalathea longimana sp. nov., holotype (ovigerous female, 6.5 mm, Philippines, Musorstom 3, Stn CP107). A, carapace and abdomen, dorsal. B, sternal plastron. C, anterior part of cephalothorax showing left antennule and antenna, ventral. D, right Mxp3, lateral. E, right pereiopod 1 palm and fingers, dorsal. F, right pereiopod 1 merus and carpus, dorsal. G, right pereiopod 3, lateral. H, right pereiopod 4, lateral. Scale bar: A, E–H, 1 mm; B–D, 2 mm.

Figure 6. Squamae on distal portion of pereiopod 1 hand, showing setae and spinules, dorsal view. A, Allogalathea babai sp. nov., holotype (ovigerous female 5.4 mm, New Caledonia, Lagoon, 8 September 1993). B, Allogalathea elegans (Adams & White, 1848) (ovigerous female 5.6 mm, New Caledonia, Touho Bank, 28 August 1993). C, Allogalathea inermis sp. nov., holotype (ovigerous female 7.3 mm, New Caledonia, SMIB 5, Stn DW100). D, Allogalathea longimana sp. nov., holotype (ovigerous female 6.5 mm, Philippines, Musorstom 3, Stn CP107).