Coralliogalathea humilis, (NOBILI, 1905)

CORALLIOGALATHEA HUMILIS ( NOBILI, 1905) View in CoL

( FIGS 4, 5A, B)

Galathea humilis Nobili, 1905: 397 . – Nobili, 1906a: 124, pl. 8, fig. 4. – Doflein & Balss, 1913: 169 [list]. – Lewinsohn, 1969: 117, fig. 22.

Coralliogalathea humilis ( Nobili, 1905) View in CoL : Baba & Javed, 1974: 62. – Tirmizi & Javed, 1993: 37, fig. 16.

Material examined

Syntypes: Red Sea. Djibouti, H. Coutiere, collected, 1897: three M, 1.9–2.0 mm, two ov. F, 2.1–2.3 mm (MNHN-IU-2013-17324) .

Red Sea. Saudi Arabia. Farasan Banks, Dolphen Lagoon, 19.0053°N, 40.1482°E, 1–7 m, 4 March 2013: one ov. F, 2.0 mm ( UF36151 ) GoogleMaps . – Farasan Banks, Marca Is., 18.2206°N, 41°3244°E, 5–15 m, 6 March 2013: one ov. F, 2.1 mm ( UF36158 ) . – Farasan Is., Zahrat Durakah, 16.8359°N, 42.3063°E, 2–6 m, 11 March 2013: one M, 1.6 mm ( UF37026 ) GoogleMaps . – Al Lith, 20.1672°N, 40.2233°E, 1–2 m, 21 March 2013: one ov. F, 2.1 mm ( UF37156 ) GoogleMaps . – off Thuwai, Abu Shosha Reef, 22.2044°N, 39.047°E, 7–8 m, 23 March 2013: three M, 1.4–1.6 mm ( UF37403 ) GoogleMaps .– Jaz’air, 27.6384°N, 35.3062°E, 10 m, 27 September 2013: one ov. F, 2.7 mm, one F, 1.3 mm ( UF36439 ) GoogleMaps . – Gulf of Aqaba , 28.4039°N, 34.7407°E, 7–8 m, 29 September 2013: one M, 1.4 mm ( UF38080 ) GoogleMaps . – 28.1846°N, 34.6381°E, 3–10 m, 1 October 2013: one M, 1.2 mm ( UF38193 ) GoogleMaps . – Shi’b Al Khamsa, 38.6163°N, 22.7489°E, 8 m, 6 March 2014: one M, 1.7 mm ( UF40269 ) GoogleMaps . – Wajh Barrier, 25.407°N, 36.690°E, 5–7 m, 30 January 2016: one ov. F, 1.9 mm ( UF42374 ) GoogleMaps . – Wajh Barrier, 25.407°N, 36.690°E, 5–7 m, 30 January 2016: one ov. F, 2.3 mm ( UF42390 ) GoogleMaps .

Madagascar. Tulear, coll. Thomassin. Stn 489: one ov. F, 2.5 mm (MNHN-IU-2013-17320). – Stn 498, one M, 2.2 mm (MNHN-IU-2013-17322). – Stn 617, one M, 1.8 mm (MNHN-IU-2013-17309). – Stn 678, one juv., 1.0 mm (MNHN-IU-2013-17310). – Stn 761, two M, 1.7–1.8 mm, one F, 1.6 mm, one juv., 1.0 mm (MNHN-IU-2013-17312). – Stn 762, one juv., 1.0 mm (MNHN-IU-2013-17316). – Stn 775, one M, 1.8 mm, one F, 1.6 mm (MNHN-IU-2013-17313). – Stn 844B, two M, 1.5–1.9mm,five F, 1.5–2.4mm (MNHN-IU-2013-17319). – Stn 896, nine M, 1.2–2.2 mm, five ov. F, 2.2–2.6 mm, two F, 1.9–2.1 mm (MNHN-IU-2013-17311). – Stn 902A, two M, 1.8–1.9 mm, one ov. F, 1.9 mm, one F, 1.7 mm (MNHN-IU-2013-17318). – Stn 1635, one ov. F, 2.0 mm, one juv., 1.0 mm (MNHN-IU-2013-17315) .

Other material: Red Sea. Djibouti. Moucha Is., Maskali Bank, 11.6992°N, 43.1432°E, 7–17 m, 27 September 2012: two M, 1.3–2.0 mm, one ov. F, 1.6 mm ( UF33346 ) GoogleMaps .

Red Sea. Jubal, Gulf of Suez, Routh reef, Col. Dolfus, 29 December, 1928:oneF, 1.1 mm (MNHN-IU-2013-17321).

Red Sea. Sudan. Stn SAN46, Al Bahr al Ahmar. Sanganeb , 9 m, 25 March 1991: one ov. F, 2.6 mm ( SMF) . – Stn SAN12, Al Bahr al Ahmar. Sanganeb , S-Jetty, E-Side, 2 m, 4 April 1991: six M, 1.6–2.0 mm, three ov. F, 1.6–2.4 mm, four F, 1.6–1.8 mm ( SMF) . – Stn SAN3, Al Bahr al Ahmar. Sanganeb , N-Jetty, E-side, 1 m, 5 April 1991: seven M, 1.7–2.4 mm, four ov. F, 1.8–2.3 mm, five F, 1.6–1.8 mm ( SMF) . – Stn SAN2, Al Bahr al Ahmar, Sanganeb , S-Jetty, W-side, 1 m, in Stylophora , 6 April 1991: four M, 1.5–2.0 mm, three ov. F, 1.8–2.0 mm, two F, 1.5–1.6 mm ( SMF) . – Stn SAN8, Al Bahr al Ahmar. Sanganeb , S-Jetty, W-side, 1 m, 6 April 1991: four M, 1.5– 2.0mm, seven ov.F, 1.6–2.3 mm, two F, 2.0– 2.1 mm ( SMF) . – Stn SAN13, Al Bahr al Ahmar. Sanganeb , N-Jetty, reefplateau, 1 m, 8 April 1991: three M, 1.7–2.0 mm, four ov. F, 2.1–2.5 mm, one F, 1.6 mm ( SMF) . – Stn SAN25, Al Bahr al Ahmar. Sanganeb , 11 m, 8 April 1991: one M, 2.2 mm ( SMF) . – Stn SAN28, Al Bahr al Ahmar, 9 April 1991: one ov. F, 2.1 mm ( SMF) . – Stn SAN45, Al Bahr al Ahmar, 15 April 1991: three M, 2.2–2.5 mm, one ov. F, 2.5 mm, one F, 2.6 mm ( SMF) . – Stn SAN167, Al Bahr al Ahmar. Port Sudan, Wingate Reef , 7 m, in living Pocillopora sp. , 19 September 1992: one ov. F, 2.8 mm ( SMF) . – Stn SAN115, Al Bahr al Ahmar. Sanganeb , 1 m, 26 September 1992: five M, 2.1–2.5 mm, two ov. F, 2.4–2.5 mm, two F, 2.1–2.2 mm ( SMF) . – Stn SAN117, Al Bahr al Ahmar. Sanganeb , S-Jetty, 14 m, 27 September 1992: two F, 2.0– 2.1 mm ( SMF) . – Stn SAN127, Al Bahr al Ahmar, 29 September 1992: one M, 2.0 mm, one ov. F, 2.1 mm ( SMF) . – Stn SAN125, Al Bahr al Ahmar. Sanganeb , 14 m, 30 September 1992: one ov. F, 2.1 mm ( SMF) . – Stn SAN129, Al Bahr al Ahmar. Sanganeb , N-Jetty, 1 m, 1 October 1992: one M, 2.2 mm ( SMF) . – Stn SAN148, Al Bahr al Ahmar. Sanganeb , 22 m, 3 October 1992: one M, 2.0 mm, one ov. F, 1.8 mm ( SMF) . – Stn SAN106, Al Bahr al Ahmar. Sanganeb , 6–10 m, 3 October 1993: one ov. F, 2.2 mm ( SMF) . – Rabigh, Stn SAN1, coast guard, 7 April 2011: one M, 2.4 mm ( SMF) .

Red Sea. Jeddah , 21.88483°N, 38.9727°E, 0.5 m, 17 April 2011: four M, 1.5–2.0 mm, one ov. F, 1.6 mm ( SMF) GoogleMaps .

Madagascar. Tulear, coll. Thomassin, Stn 1666, two ov. F, 1.8–2.1 mm (MNHN-IU-2013-17317). – No Stn number: one juv., 1.0 mm (MNHN-IU-2013-17323), one ov. F, 2.0 mm (MNHN-IU-2013-17314) .

Description

Carapace: 1.1–1.3 times broader than long; cervical groove distinct, laterally bifurcated; most ridges on gastric region interrupted, with some scattered scale-like ridges; one scale-like epigastric ridge; two protogastric ridges, anterior ridge medially interrupted, posterior ridge short, arcuate, slightly prominent, with thick plumose setae; one mesogastric ridge, medially interrupted, not extending to anteriormost marginal branchial spines; one metagastric ridge, not medially interrupted and not extending to anterior branchial ridges. Anterior branchial region with distinct ridges. Mid-transverse ridge usually uninterrupted, preceded by shallow cervical groove, followed by three transverse ridges, two of them uninterrupted. Lateral margins slightly convex medially, with five or six spines: one spine in front of and four or five spines behind anterior cervical groove; first spine anterolateral, small, at level of orbit, located at midlength between outer orbital spine and anteriormost spine of branchial margin; two spines on anterior branchial margin, and two or three spines on posterior branchial margin; third spine, when present, very small. Strong outer orbital spine. Rostrum spatulate, horizontal, slightly longer than broad, length 0.4 and breadth 0.3 that of carapace; dorsal surface nearly horizontal in lateral view, concave at base; lateral margin with three incised sharp teeth; margin between proximal and median spines straight. Pterygostomian flap rugose, with one distinct spine on upper margin near linea anomurica, with sparse short setae, anterior margin bluntly angular.

Sternum: Nearly as long as broad; lateral extremities gently divergent posteriorly. Third sternite triangular, 1.2 times wider than long.

Abdomen: Somites 2–3 each with uninterrupted transverse ridge on tergite behind anterior ridge; somite 4 smooth or with minute setose scales on tergite; somites 5 and 6 smooth, posteromedian margin of somite 6 straight.

Eyes: Ocular peduncles as long as broad, maximal corneal diameter 0.7 of rostrum width.

Antennule: Article1 with two well-developed distodorsal and distolateral mucronated spines, distodorsal larger; one small distomesial spine and one minute distomesial spine on dorsal side. Ultimate article without a tuft of fine setae on distodorsal margin.

Antenna: Article 1 with strong distomesial spine barely reaching distal margin of article 2.

Mxp3: Ischium with spine on flexor distal margin; crista dentata with eight to ten denticles. Merus as long as ischium; flexor margin with one strong spine; extensor margin with one distal spine. Carpus unarmed.

P1: Males 2.1–3.6 and females 1.6–2.1 times carapace length. Merus 0.7–0.8 length of carapace, 1.5–1.7 times as long as carpus, with some dorsomesial and a few ventromesial spines. Carpus 1.0–1.5 length of palm, 1.7–2.5 times as long as broad; dorsal surface with small spines; mesial row of spines, median spine strong. Palm 1.3–1.4 times as long as broad, unarmed. Fingers unarmed, 0.9–1.3 length of palm, each finger distally with two rows of teeth, spooned.

P2–4: With setose striae and some long plumose setae. P2 1.8 times carapace length. Meri successively shorter posteriorly (P3 merus 0.8 length of P2 merus, P4 merus 0.9 length of P3 merus); P2 merus 0.5 carapace length, 3.2 times as long as broad, as long as P2 propodus; P3 merus 3.0 times as long as broad, as long as P3 propodus; P4 merus 2.7 times as long as broad, 0.9 length of P4 propodus. Extensor margins of meri with row of three or four proximally diminishing spines on P2–3, unarmed on P4; flexor margins distally ending in small spine followed proximally by several eminences; lateral sides unarmed. Carpi with no or one distal spine on extensor margin; lateral surface with several acute granules sub-paralleling extensor margin on P2–4; flexor distal margin with small spine. P2–4 propodi 4.0–5.8 times as long as broad; extensor margin unarmed; flexor margin with three or four slender, movable spines on P2–4. Dactyli distally ending in well-curved strong spine, length 0.6–0.7 that of propodi.

Coloration: Base colour of carapace, abdomen and pereiopods light brown. Anterior half of abdomen sometimes with brown median longitudinal stripe. Most distal portion of pereiopod articles darker.

Remarks

Coralliogalathea humilis View in CoL is easily distinguished from C. tridentirostris ( Miyake, 1953) View in CoL from Japan by the shape of the rostrum, which is clearly wider (measured between the proximal spines) than long (measured between proximal spines and the tip of rostrum) in C. tridentirostris View in CoL ; in C. humilis View in CoL , the rostrum is as long as, or longer than, it is wide.

Furthermore, C. humilis View in CoL can be differentiated from C. megalochira View in CoL , C. minuta View in CoL and C. parva View in CoL by its absence of a transverse stria in the fourth abdominal somite, a third sternite that is wider than long and a metagastric ridge of the carapace that is usually uninterrupted. In the other three species, the fourth abdominal somite has a transverse stria behind the anterior ridge, the third sternite is longer than, or as long as, it is wide, and the metagastric ridge of the carapace is usually medially interrupted.

Based on molecular analyses, the most closely related species to C. humilis is C. minuta , with divergence values of 9.2% for COI and 2.4% for 16S. The greatest divergence observed was between C. humilis and C. tridentirostris (14.1 and 12.2% for COI and 16S, respectively). Average intraspecific distances in C. humilis were 0.3 and 0.2% for COI and 16S, respectively ( Table 2).

Distribution

Red Sea, Madagascar, from 0.5 to 17 m, on stones and dead and living corals ( Stylophora sp. , Acropora sp. , Seriatopora sp. and Pocillopora sp. ).