Galathea inconspicua Henderson, 1885

Macpherson, Enrique & Robainas-Barcia, Aymee, 2015, Species of the genus Galathea Fabricius, 1793 (Crustacea, Decapoda, Galatheidae) from the Indian and Pacific Oceans, with descriptions of 92 new species, Zootaxa 3913 (1), pp. 1-335 : 145-149

Galathea inconspicua Henderson, 1885

( Figs 50 , 51 A–C, 117E)

Galathea inconspicua Henderson, 1885: 408 (off Banda Island, 659 m).— Henderson, 1888: 122, pl. 12, fig. 2 (off Banda Island, 659 m).— Baba, 1994: 4, fig. 2 (off Central Queensland, 296–303 m).— Davie, 2002: 61 (list).— Baba, 2005: 244 (key, synonymies).—Baba et al., 2008: 69 (compilation).

Not Galathea inconspicua . — Dong & Li, 2010: 12 , fig. 7 (South China Sea, 158-220 m) (= Galathea perone n. sp.).

Dubious identification.

Galathea inconspicua . — Poore et al., 2011: 332, pl. 10I (color photo, Philippines).

Material examined. Vanuatu. MUSORSTOM 8, Stn CP1017, 17°52,80'S, 168°26,20'E, 294–295 m, 27 September 1994: 2 ov. F 3.7–4.3 mm (MNHN-IU-2013-9700).—Stn CP1087, 15°10.18'S, 167°14.07'E, 394–421 m, 6 October 1994: 1 ov. F 6.2 mm (MNHN-IU-2013-9699). BOA 0, Stn CP2318, 15°05.66'S, 166°54.765'E, 415–475 m, 16 November 2004: 1 F 3.9 mm (MNHN-IU-2013-9702). SANTO, Stn AT1, 15°32.4–33.8'S, 167°16.4–19.5'E, 167–367 m, 14 September 2006: 1 M 4.8 mm, 2 ov. F 4.4–5.0 mm (MNHN-IU-2013-15866), 1 M 3.6 mm (MNHN-IU-2013-9705) 1 M 5.5 mm (MNHN-IU-2013-8504), 1 M 5.6 mm (MNHN-IU-2013- 9706).—Stn AT8, 15°40.5'S, 167°01.5'E, 366–389 m, 17 September 2006: 1 M 5.1 mm (MNHN-IU-2013- 8507).— Stn AT9, 15°41.5'S, 167°01.3'E, 481 m, 17 September 2006: 2 M 4.7–4.9 mm (MNHN-IU-2013- 8508).—Stn AT58, 15°33.0'S, 167°19.3'E, 364–390 m, 3 October 2006: 1 ov. F 4.8 mm (MNHN-IU-2013- 13949), 1 M 5.0 mm (MNHN-IU-2013-8506).—Stn AT64, 15°39.6'S, 167°01.9'E, 249–252 m, 4 October 2006: 2 F 3.1–3.9 mm (MNHN-IU-2013-9704).

New Caledonia. BIOCAL, Stn CP108, 22°02.55'S, 167°05.68'E, 335 m, 9 September 1985: 1 M 4.1 mm, 1 ov. F 3.7 mm (MNHN-IU-2013-15863). MUSORSTOM 4, Stn CP170, 18°57.00'S, 163°12.60'E, 17 September 1985: 1 ov. F 5.9 mm (MNHN-IU-2013-13961).—Stn CP241, 22°09.00'S, 167°12.20'E, 470–480 m, 3 October 1985: 1 M 2.4 mm (MNHN-IU-2013-15864). BATHUS 1, Stn DE 693, 20°35'S, 164°59'E, 308–324 m, 17 March 1993: 1 F 5.9 mm (MNHN-IU-2013-9703).— Stn CP710, 21°43'S, 166°36'E, 320–385 m, 19 March 1993: 7 M 3.7–5.6 mm, 1 F 5.0 mm (MNHN-IU-2013-9701).—Stn CP711, 21°43'S, 166°35'E, 315–327 m, 19 March 1993: 4 M 4.5–5.1 mm, 5 ov. F 3.7–4.4 mm, 1 F 4.9 mm (MNHN-IU-2013-15862). HALIPRO 1, Stn CP851, 21°43.32'S, 166°37.43'E, 314–364 m, 19 March 1994: 10 M 4.5–5.5 mm, 3 ov. F 5.0– 5.3 mm, 1 F 4.3 mm (MNHN-IU-2013- 15861).—Stn CC856, 21°44.02'S, 166°37.76'E, 311–365 m, 20 March 1994: 1 M 4.0 mm (MNHN-IU-2013- 13948). BATHUS 4, Stn CP889, 21°00.83'S, 164°27.34'E, 416–433 m, 2 August 1994: 1 M 5.8 mm (MNHN-IU- 2013-15865). TERRASES, Stn CP3807, 22°11'S, 167°12'E, 380–400 m, 25 October 2008: 2 ov. F 4.2–5.3 mm, 1 F 4.9 mm (MNHN-IU-2011-4570).

New Caledonia. Chesterfield Islands. EBISCO, Stn CP2571, 20°26.15'S, 158°45.06'E, 298–309 m, 14 October 2005: 1 M 4.4 mm (MNHN-IU-2013-8505).

Description. Carapace: Slightly longer than broad; transverse ridges with dense short setae, without long setae; cervical groove distinct, laterally bifurcated. Gastric region with some transverse ridges: 1 epigastric ridge, scale-like, with 6 or 7 small spines; 2 protogastric ridges, anterior ridge uninterrupted, medially convex, with 1 parahepatic spine on each side, posterior uninterrupted, with 1 or 2 lateral scales; 2 mesogastric ridges, anterior ridge uninterrupted and not extending laterally to anteriormost of branchial marginal spines, posterior ridge scalelike; 2 metagastric ridges, anterior ridge uninterrupted, not continuing laterally to anteriorbranchial ridge, posterior ridge short. Hepatic region with 1 small spine near first marginal (anterolateral) spine. Anterior branchial region with distinct ridges. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove. Posterior branchial region with 6 transverse ridges, 2 or 3 ridges uninterrupted. Lateral margins subparallel, with 7 or 8 spines: 2 or 3 spines in front of and 5 spines behind anterior cervical groove; first anterolateral, well-developed, slightly behind level of lateral limit of orbit, 1 or 2 small spines at midlength between anterolateral spine and anteriormost spine of branchial margin, with small spine ventral to between first and second; 2 or 3 spines on anterior branchial region, last small, and 2 or 3 spines on posterior branchial margin. Small spine on lateral limit of orbit, 1 small frontal spine between orbit and first anterolateral spine; infraorbital margin with some small spines. Rostrum narrow, 2.5 times as long as broad, length 0.7 postorbital carapace length and breadth 0.3 that of carapace; distance between distalmost lateral incisions 0.25 distance between proximalmost lateral incisions; dorsal surface nearly horizontal in lateral view, with numerous small scale-like setose ridges; lateral margin with 4 deeply incised teeth, distal pair well-developed and slightly smaller than previous pair.

Pterygostomian flap rugose, unarmed, ridges with short setae, anterior margin acute; upper margin, near linea anomurica, with numerous small teeth.

Sternum: As long as broad, lateral extremities gently divergent posteriorly.

Abdomen: Somites 2–4 each with 2 uninterrupted and 1 or 2 interrupted transverse ridges on tergite; somite 6 with 2 medially interrupted ridges. Males with G1 and G2.

Eyes: Ocular peduncles 1.7 times longer than broad, maximum corneal diameter 0.9 rostrum width.

Antennule: Article 1 with 2 well-developed distal spines, distodorsal larger, distomesial obsolescent; 2 small spines along lateral margin. Ultimate article with tuft of long fine setae on distodorsal margin.

Antenna: Article 1 with ventral distomesial spine not reaching midlength of article 2. Article 2 with 2 distal spines, distolateral spine longer than distomesial, and reaching midlength of article 3. Articles 3 and 4 unarmed.

Mxp3: Ischium with flexor margins ending in small spine, extensor margin ending in acute angle; crista dentata with 20–21 denticles. Merus as long as ischium; flexor margin with 3 spines, proximal spine clearly longer than others, median spine smaller than distal; extensor margin ending in small spine. Carpus unarmed.

P1: 8.8 times carapace length, with numerous setiferous small scales, and some scattered long setae. Merus 3.8 times carapace length, 1.9 times as long as carpus, with numerous spines, dorsomesial and distal spines stronger than others. Carpus 0.8 length of palm, 4.3 times as long as broad; dorsal surface with some small spines; mesial margin with row of spines. Palm 4.2 times longer than broad, lateral and mesial margins subparallel; small spines arranged roughly in dorsal, dorsolateral and dorsomesial rows. Fingers unarmed, 0.8 times palm length, each finger distally with two rows of teeth, spooned.

P2–4: long and slender, with some setose striae and sparse long setae. P2 1.9 times carapace length. Meri successively shorter posteriorly (P3 merus 0.8 length of P2 merus, P4 merus 0.8 length of P3 merus); P2 merus 1.9 carapace length, 6.4 times as long as broad, 1.1 times longer than P2 propodus. P3 merus 5.6 times as long as broad, 1.0 times longer than P3 propodus. P4 merus 4.0 times as long as broad, 0.8 times longer than P4 propodus. Extensor margin with row of 12 or 13 proximally diminishing spines on P2–3, 4 or 5 spines on P4; ventral margins distally ending in strong spine, lateral sides with row of small spines on P2–4. Carpi with 5–7 spines on extensor margin on P2–4; lateral surface with 4 or 5 small spines sub-paralleling extensor margin; flexor distal margin acute. Propodi 7.7–8.7 times as long as broad; extensor margin with 5–7 small proximal spines; flexor margin with 6 or 7 slender movable spines, distal two spines with another smaller spine mesial to them. Dactyli distally ending in well-curved strong spine, length 0.4–0.5 that of propodi; flexor margin with 8 or 9 proximally diminishing teeth, terminal one prominent and larger than penultimate.

Epipods present only on P1.

Coloration. Overall light brown or orange.

Remarks. Galathea inconspicua was originally described by Henderson (1885) on the basis of one male specimen from Banda Island. The holotype is now broken, without pereiopods and then it is difficult to assess diagnostic characters. Furthermore, the illustrations given by Henderson are not accurate ( Baba 1994) and the description is very short. Therefore, the differences among G. inconspicua and the closely related species are not easy to establish. Unfortunately, we have no specimens from the type locality, and sometimes more than one closely related species is found in samples from same stations. For these reasons, we have considered the description and illustrations by Baba (1994) representing the true G. inconspicua .

Galathea inconspicua belongs to the group of species with uninterrupted gastric ridges on the carapace, the carapace lateral margin armed with one small but distinct spine between the anterolateral spine and the anteriormost branchial marginal spine, the antennular basal article only with two well-developed terminal spines and the extremely narrow rostrum (2.5–3.5 times longer than broad). This group contains six closely related species, including five new species: G. ganindo n. sp. from the Philippines to New Caledonia, G. inconspicua from Indonesia to New Caledonia, G. perone n. sp. from the Philippines, G. rhaphidia n. sp. from Fiji and Tonga, G. scolopia n. sp. from Papua New Guinea and Vanuatu, G. tribulosa n. sp. from the Solomon Islands. These species can be distinguished from one another by the following characters:

Galathea ganindo n. sp. can be distinguished from the other species by the presence of two epigastric spines only on the carapace, rather than four or more spines in the other species.

Galathea perone n. sp. is easily recognized by the absence of hepatic spines, which are always present in the other species.

Galathea rhaphidia n. sp. closely resembles G. scolopia , G. inconspicua and G. tribulosa . They can be differentiated by the number of ridges on the abdominal somites 2–3, i.e., having two uninterrupted ridges in G. rhaphidia , instead of 4 in the other species. Galathea rhaphidia further differs from G. inconspicua and G. tribulosa by the interrupted, scale-like anterior protogastric ridge, rather than being not interrupted in the latter two species.

Galathea inconspicua is closest to G. tribulosa , but the two can be distinguished by the following characters:

- The rostrum has the distal pair of spines minute, clearly smaller than the second pair in G. tribulosa , whereas these distal spines are well-developed, and slightly smaller than the second pair in G. inconspicua . - The ratio between the distance between the sinus of the distal pair of lateral spines of the rostrum and the distance between the sinus of the proximal pair is less than 0.25 in G. tribulosa , rather than more than 0.25 in G. inconspicua .

The smallest genetic distances among species pairs are observed between G. ganindo and G. perone (8.8% COI) and between G. tribulosa and G. rhaphidia (9.6% COI). The other pairwise comparisons are larger ( Tab. 2 ). Distribution. Previous records from Indonesia (Banda Island) and central Queensland, 296– 659 m. Newly recorded from Vanuatu, New Caledonia, Chesterfield Islands, 167– 480 m.

Figures

FIGURE 50. Galathea inconspicua Henderson, 1885, male, 5.6 mm, Vanuatu (MNHN-IU- 2013 - 9706). A, carapace and abdomen, dorsal view; B, thoracic sternites 3 and 4; C, left part of cephalothorax, ventral view, showing antennular and antennal peduncles, and anterior part of pterygostomian flap; D, ischium, merus and carpus of right Mxp 3, lateral view; E, right P 1 merus and carpus, dorsal view; F, right P 1 palm and fingers, dorsal view; G, right P 2, lateral view; H, right P 2 dactylus, lateral view; I, right P 3, lateral view; J, right P 4, lateral view. Scale: A, E, F, G, I, J = 1 mm; B – D, H = 0.5 mm.

FIGURE 51. Rostrum, dorsal view. Galathea inconspicua Henderson, 1885: A, Chesterfield Islands, male, 4.4 mm (MNHN- IU- 2013 - 8505); B, Vanuatu, ovigerous female, 4.8 mm (MNHN-IU- 2013 - 13949); C, Vanuatu, male, 5.5 mm (MNHN-IU- 2013 - 8504). Galathea tribulosa n. sp.: D, Solomon Islands, male, 3.8 mm (MNHN-IU- 2013 - 15859); E, Solomon Islands, ovigerous female, 5.8 mm (MNHN-IU- 2013 - 15858); F, Solomon Islands, ovigerous female, 6.2 mm (MNHN-IU- 2013 - 15860). Scale = 1 mm.