Allogalathea inermis, 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 : 260-261

Allogalathea inermis sp. nov. ( Figs 4 , 6C )

Galathea elegans Miyake, 1938: 37 , figure 1, plate 2, figure E (in part); Melin, 1939: 77, figures 48–53 (in part); Utinomi, 1956: 63, plate 32, colour figure 4.

Allogalathea elegans Baba, 1969: 6 , figure 1 (in part); Baba, 1979: 654 (in part); Baba, 1988: 54 (in part).

Material examined: Mozambique. Mainbaza. Stn DW 3168, 26°12′S, 35°3′E, depth 87–90 m, Richer de Forges & Corbari coll., 16 April 2009: one M 6.4 mm (MNHN-Ga7362, Allo42) .

Thailand. Phuket. Coral reefs: one M 3.9 mm (MNHN-Ga7363, Allo28), one F 4.9 mm (MNHN- Ga7364, Allo27).

Indonesia Rumphius Expedition II, in front of Kotasirih village, Kailakat Bay, Gorong Island, 25 January 1975: one M 1.7 mm, one F 1.8 on Himerometra robustipinna (MNHN-Ga 1125).

Vanuatu. Espiritu Santo, Santo 2006. Stn NR 8, 15°35.7′S, 167°07.4′E, 15 September 2006, 11 m: 1 M 3.1 mm (MNHN-Ga7365, Allo30), one ovig. F 3.6 mm (MNHN-Ga7366, Allo12) .

New Caledonia. Touho Bank, 28 August 1993: one M 3.8 mm, one ovig. F 5.1 mm, one F 3.5 mm (MNHN-Ga7367); Touho, depth 10 m, one ovig. F 4.4 mm (MNHN-Ga7418).

Lagoon. Across from Kohe, 8 September 1993: one M 5.1 mm (MNHN-Ga7368, Allo32).

New Caledonia. SMIB 5. Stn DW 100, 23°22.90′S, 168°05.20′E, 14 September 1989, depth 80–120 m: one ovig. F 7.3 mm (MNHN-Ga7369, Allo3) .

Chesterfield Islands . Corail 2. Stn CP 7, 20°52′S, 161°37′E, 20 July 1988, depth 63–64 m: one M 4.5 mm, one ovig. F 4.8 mm (MNHN-Ga7370); Stn CP 90, 19°03′S, 158°56′E, 26 July 1988, depth 44–48 m: one ovig. F 4.9 mm (MNHN-Ga7371) .

Types: The ovigerous female of 7.3 mm postorbital carapace length, from New Caledonia ( SMIB 5 , Stn DW 100, MNHN-Ga7369) has been selected as the holotype . All the other specimens are paratypes.

Etymology: From the Latin inermis (unarmed), referring to the absence of spinules on most squamae of P1.

Description: Carapace, exclusive of rostrum 0.9 times as long as broad; dorsal surface nearly horizontal from anterior to posterior, and cervical groove slightly distinct. Gastric region with five or six uninterrupted and two or three interrupted ridges, usually with some scales between them, anterior first, third, and fourth uninterrupted ridges medially convex anteriorly; mid-transverse ridge uninterrupted, extending laterally to fifth marginal spines, preceded by cervical groove, followed by five or six transverse ridges. Lateral margins with eight or nine spines: two spines in front of and six spines behind cervical groove; first anterolateral, small, 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 four spines on posterior branchial margin, with the last very small. Rostrum 1.3–1.6 times as long as broad, with eight or nine lateral small teeth, length 0.7 that of carapace, dorsal surface nearly horizontal in lateral view, with small setiferous ridges ( Fig. 4A ).

Pterygostomian flap with some ridges, anterior margin bluntly produced.

Sternal plastron 0.8 times as long as broad, lateral limits divergent posteriorly. Sternite 3 2.6 times as broad as long, anterior margin with small median notch. Sternite 4 2.6 times longer and 2.4 times broader than preceding sternite, 0.4 times as long as broad; sternites 4 and 5 with some transverse ridges bearing long setae ( Fig. 4B ).

Abdominal somites 2–4 each with two or three uninterrupted transverse ridges on tergite, with or without scales in between; somite 5 with two uninterrupted ridges, somite 6 with two 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 hardly visible from dorsal view, with distomesial spine reaching midlength of article 2. Article 2 with distolateral spine as long as distomesial, overreaching midlength of article 3, sometimes additional mesial spine. Article 3 with small, distinct distomesial spine. Article 4 unarmed ( Fig. 4C ).

Mxp3 ischium with well-developed spine on flexor distal margin; extensor margin unarmed; crista dentata with 19–24 denticles. Merus slightly longer than ischium, with two strong spines of subequal size on flexor margin, proximal one located at midlength, distal one at terminal end; extensor margin with three or four spines ( Fig. 4D ).

P1 squamous, 2.0–2.5 times carapace length, subcylindrical, most dorsal squamae lack spinules, and with numerous long setae. Merus 0.8 times length of carapace, 1.4–1.6 times as long as carpus, with row of mesial and distodorsal spines. Carpus 0.6–0.7 times the length of palm, 1.5–1.6 times longer than broad, lateral and mesial margins subparallel, with row of spines along mesial and distodorsal margins. Palm 1.7–1.8 times longer than broad, lateral and mesial margins convex in adult males (slightly in females); mesial margin with row of spines, lateral margin with row of spines continuing on to whole lateral margin of fixed finger, and most scales on dorsal surface without spinules. Fingers as long as palm, distally crossing when closed; opposable margins nearly straight; mesial margin of movable finger with trwo or three subterminal spines ( Fig. 4E ).

P2–P4 squamous, weak in armature, relatively slender, somewhat compressed, with long setae. P2 1.5 times carapace length. Meri successively shorter posteriorly (P3 merus 0.9 times length of P2 merus, P4 merus 0.9 times length of P3 merus); P2 merus 0.5–0.6 times carapace length, 3.5 times as long as broad, 1.2–1.5 times longer than P2 propodus. Dorsal margins of meri with distal spine and row of small proximally diminishing spines on P2–P3, nearly unarmed on P4; ventrolateral margins with strong terminal spine. Carpi with some dorsal spines on P2 and P3, unarmed on P4; flexor distal margins with very small distal spine. Propodi subequal in length on P2 and P3, slightly shorter on P4, 3.3–3.4 times as long as broad on P2; extensor margin unarmed; flexor margin with six or seven slender movable spines. Dactyli subequal in length, 0.6 times the length of propodi, ending in a curved, strong, sharp spine; flexor margin with prominent triangular terminal tooth preceded by four or five obsolescent teeth, each with seta-like movable spine ( Fig. 4F–H ).

Epipods present on P1, absent on P2–3.

Colour: Three patterns have been observed: carapace and abdomen uniformly dark, usually brown or red (pattern 1 of Baba, 1979), dark brown with two narrow light stripes (pattern 3 of Baba, 1979), and alternating dark and light longitudinal stripes (pattern 4 of Baba, 1979) (see Appendix). Pereiopods uniformly dark (red or brown) or yellowish.

Remarks: Allogalathea inermis sp. nov. is easily differentiated from the other closely related species ( A. babai sp. nov. and A. elegans ) by the following features.

1. The rostrum is shorter in A. inermis sp. nov. (1.3– 1.6 times longer than wide) than in A. babai sp. nov. and A. elegans (2.0–2.3 times longer than wide).

2. The squamae on the dorsal surface of the P1 palm are mostly unarmed in A. inermis sp. nov., whereas these squamae have at least one spinule in A. babai sp. nov. and A. elegans .

3. The mesial and lateral margins of P1 palm are convex in the adult males of A. inermis sp. nov., whereas these margins are straight in A. babai sp. nov. and A. elegans .

Distribution and habitat: Mozambique, Japan, Thailand, Indonesia (Gorong Island), Vanuatu, New Caledonia, and Chesterfield Islands, between a depth of

44 and 120 m. Usually living on crinoids ( O. bennetti and H. robustipinna ).

Figures

Figure 4. Allogalathea inermis sp. nov., holotype (ovigerous female 7.3 mm, New Caledonia, SMIB 5, Stn DW100). 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, dorsal. F, right pereiopod 2, lateral. G, right pereiopod 3, lateral. H, left 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).