Galathea brevimana

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 : 70-72

Galathea brevimana Paul’son, 1875

( Fig. 19 )

Galathea brevimana Paul’son, 1875: 95 (Ras Muhammad, Red Sea).— Nobili, 1906: 128 (Red Sea).— Doflein & Balss, 1913: 169 (Dahab, Berenice, Egypt).— Lewinsohn, 1969: 105, fig. 19 (Red Sea, 0–3 m).— Tirmizi & Javed, 1993: 53, fig. 25 (Indian Ocean).—Baba et al., 2008: 67 (compilation).

? Galathea australiensis .— Balss, 1915: 2 (not G. australiensis Stimpson, 1858 ).

Material examined. Red Sea. Jubal, 29 December 1928: 1 M 2.7 mm, 1 ov. F 3.0 mm ( MNHN Ga752). Red Sea. Gulf of Aqaba. Stn AQ55, 13 m, 11 July 1995: 2 M 3.3–3.8 mm, 1 ov. F 4.3 mm, 6 F 2.8–4.5 mm ( SMF).—Stn AQ80, 25 m, 14 July 1995: 1 M 3.0 mm, 4 F 2.7–3.2 mm ( SMF).— Stn AQ129, 5 m, 22 July 1995: 2 M 2.6–5.7 mm, 1 F 4.7 mm ( SMF). Red Sea. Sudan, Al Bahr al Ahmar, Sanganeb. Stn SAN113, 30 m, 27 September 1992: 1 ov. F 2.8 mm, 1 F 2.0 mm ( SMF). Red Sea. 16°43.08'N, 42°03.934'E, 0.5–1 m, 20 February 2012: 1 M 6.0 mm ( SMF). Red Sea, Farasan Island. 16°43.130'N, 42°03.902'E, 0–5 m, 23 February 2012: 1 ov. F 4.0 mm ( SMF). Red Sea. Saudi Arabia, Jaz'air, 27.6384°N, 35.3062°E, 10 m, 27 September 2013: 2 F 2.0– 2.2 mm (UF36438).

Description. Carapace: slightly longer than broad; transverse ridges with dense short non-iridescent setae, without long setae; cervical groove distinct, laterally bifurcated. Gastric region with some transverse ridges: 1 epigastric ridge medially interrupted, with 1 pair of spines; 2 protogastric ridges, anterior one uninterrupted, convex medially, extending laterally to second marginal spine, without parahepatic spines; some scales between epigastric and protogastric ridges, posterior protogastric ridge moderately short, convex; 1 mesogastric ridge uninterrupted but not extending laterally to anteriormost of branchial marginal spines; 2 metagastric ridges moderately short, uninterrupted, not extending laterally to anterior branchial region. Anterior branchial region with distinct ridges. Mid-transverse ridge uninterrupted, preceded by shallow cervical groove, followed by 5 transverse ridges. Lateral margins well convex medially, with 8 spines: 2 spines in front of and 6 spines behind anterior cervical groove; first anterolateral, well-developed, at same level of lateral limit of orbit, with spine ventral to between first and second spines; second spine small; 3 spines on anterior branchial region, last small, and 3 spines on posterior branchial margin, last small. Small spine on lateral limit of orbit; infraorbital margin with strong spine. Rostrum 1.5–1.8 as long as broad, length 0.6–0.7 postorbital carapace length and breadth 0.4 that of carapace; distance between distalmost lateral incisions 0.2 distance between proximalmost lateral incisions; dorsal surface nearly horizontal in lateral view, with some short setae; lateral margin with 4 deeply incised sharp teeth.

Pterygostomian flap rugose, unarmed, ridges with short setae, anterior margin blunty produced.

Sternum: 0.9 times as long as broad, lateral extremities gently divergent posteriorly.

Abdomen: Somites 2–3 each with 2 or 3 uninterrupted transverse ridges on tergite and usually 1 additional interrupted ridge; somites 5 and 6 each with 2 medially interrupted ridges; posteromedian margin of somite 6 straight. Males with G1 and G2.

Eyes: Ocular peduncles 1.3 times longer than broad, maximum corneal diameter 0.7 rostrum width.

Antennule: Article 1 with 3 well-developed distal spines, distodorsal larger, distomesial spine smaller. Ultimate article twice longer than broad, with a few short fine setae not in tuft on distodorsal margin.

Antenna: Article 1 with distomesial spine exceeding distal margin of article 2. Article 2 with 2 well-developed distal spines, distolateral spine slightly longer than distomesial, both exceeding midlength of article 3. Article 3 with small distomesial spine; article 4 unarmed.

Mxp3: Ischium with small spine on flexor and extensor distal margins; crista dentata with 24 or 25 denticles. Merus as long as ischium; flexor margin with 2 spines, proximal slightly larger than distal; extensor margin unamed. Carpus unarmed.

P1: 2.1–2.3 times carapace length, covered with finely setiferous scales, with scattered long setae, a few of them iridescent. Merus 0.7–0.8 times length of carapace, 2.0–3.1 times as long as carpus, with spines arranged roughly in rows, dorsomesial spines stronger; distal spines prominent. Carpus 0.6–1.1 length of palm, 1.3–1.8 times as long as broad; dorsal and lateral surfaces with some spines; mesial margin with 3 or 4 spines (distal second strong). Palm 1.3–1.5 times longer than broad, lateral and mesial margins slightly convex; spines arranged roughly in dorsolateral and dorsomesial rows, some small spines scattered on dorsal side; dorsolateral row continuing along entire fixed finger. Fingers slightly longer than palm; each finger distally with two rows of teeth, spooned; mesial margin of movable finger with some small spines.

P2–4: moderately slender, with setose striae and sparse long setae, some of them iridescent. P2 1.8 times carapace length. Meri successively shorter posteriorly (P3 merus 0.9 length of P2 merus, P4 merus 0.8 length of P3 merus); P2 merus 0.6–0.8 carapace length, 3.1–3.7 times as long as broad, 1.2–1.7 times longer than P2 propodus. Extensor margin of P2–3 meri with row of 8–10 proximally diminishing spines, 2 or 3 on P4; lateral sides unarmed on P2–3, with row of 4 spines on P4; distoflexor angle of P2–4 with 2 spines, flexor margin with 0–1 spines and several eminences. Carpi with 4-6 spines on extensor margin on P2–3, 0–2 spines on P4; lateral surface with 2 or 3 small spines sub-paralleling extensor margin; flexor distal margin acute. P2–4 propodi 3.5–4.2 times as long as broad; extensor margin with 4–7 proximal spines; flexor margin with 3–5 movable spines. Dactyli distally ending in well-curved strong spine, length 0.6–0.8 that of propodi; flexor margin with 4 or 5 proximally diminishing teeth, terminal one prominent.

Epipods present on P1.

Remarks. Galathea brevimana was described from one female specimen collected in Ras Muhammad, Red Sea. The type material is lost, and the original description is very short; no illustrations were given. A few diagnostic characters mentioned in the original description match quite well with the present material collected near the type locality. The description and illustrations based on material from the Gulf of Aqaba by Lewinsohn (1969) agree with the present material. However, the specimens collected by Tirmizi & Javed (1993) present a few differences (e.g. presence of a mesogastric ridge extending laterally to branchial margins) and need further study.

Galathea brevimana is easily differentiated by the presence of two spines on the flexor distal angle of P2–4 meri. Only G. hydrae n. sp. from Mozambique, G. l e p i d o t a n. sp. from the Philippines to Solomon Islands and G. magnifica Haswell, 1882 from New South Wales, Australia, similarly have two spines on those angles.

Galathea lepidota and G. magnifica can be easily differentiated from G. b rev i m a n a by the ridges on the gastric area. These ridges are interrupted in short scales in G. l e p i d o t a and G. magnifica , instead of mostly complete in G. brevimana .

Galathea hydrae can be distinguished from G. brevimana by the presence of four or more epigastric spines, instead of only two spines in G. brevimana . Furthermore, G. brevimana has epipods on P1 only, and on P 1–3 in G. hydrae .

No genetic data are available from G. brevimana .

Distribution. Red Sea, 0– 30 m.

Figures

FIGURE 19. Galathea brevimana Paul’son, 1875, male, 5.7 mm, Red Sea (SMF). 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, dorsal view; F, right P 2, lateral view; G, right P 3, lateral view; H, right P 4, lateral view. Scale: A, F – H = 1 mm; E = 2 mm; B – D = 0.5 mm.