Tetralia aurantistellata, Trautwein, Sandra E., 2007

Trautwein, Sandra E., 2007, Four new species of coral crabs belonging to the genus Te tra li a Dana, 1851 (Crustacea, Decapoda, Brachyura, Tetraliidae), Zootaxa 1450, pp. 1-20 : 3-7

Tetralia aurantistellata , new species

(Pl. 2, Figs. A-F; Pl. 6, Fig. A; Pl. 7, Fig. A; Pl. 8, Fig. A)

Type material: Holotype, LACM CR 2002-043.1 (1 male) Fiji, Viti Levu island (17°27’S, 177°23'E), collected by scuba diving on patch reef from Acropora sp., depth 5 m, Sept. 26, 2002, S. Trautwein coll. Allotype, LACM CR 2002-043.2 (1 ovigerous female), same collection data.

Other material examined (total of 40 specimens): Fiji. Viti Levu island (17°27’S, 177°23'E), LACM CR 2002-044.1 (1 male, 1 ovig. female, 1 juvenile, depth 1 m, Sept. 24, 2002, S. Trautwein coll.), LACM CR 2002-044.2 (1 male, depth 1 m, Sept. 24, 2002, S. Trautwein coll.).

New Caledonia. Loyalty Is., MNHN B29229 (1 male, 2 ovig. female), MNHN B29228 (1 male, 1 ovig. female), MNHN B29227 (1 ovig. female), MNHN B29232 (4 male, 5 ovig. female), MNHN B29230 (1 male, 1 ovig. female), MNHN B29231 (7 males, 12 females).

Philippine Is. Bohol, Panglao Is., ZRC R47 (1 male, 1 ovig. female, June 16, 2004), ZRC B16 (1 male, 1 ovig. female, June 17, 2004).

Description. Carapace: Carapace quadrilateral, lenticular in both sexes (Plate 2A); carapace width exceeding length ( Table 1 ); anterolateral margins parallel in males, slightly convex to parallel in females; exterior orbital angle sharply pointed in both sexes (Plate 2B); frontal margin finely denticulate, nearly smooth with 3–5 most lateral teeth very widely spaced (dentate), notch may be present or absent (Plate 6A), few long setae scattered between teeth.

Chelipeds: Chelipeds markedly unequal, especially in males (major cheliped propodus much wider, longer than minor) (Plate 2A). Tomentose pit of major cheliped measures approximately 1/4–1/3 propodus length in females (Plate 2E), greatly reduced in males, barely extending beyond proximal margin of propodus; several long setae distributed throughout tomentose pit in females, absent in males; thickness of propodus uniform along entire length, creating a very square ventral “elbow” and concave inner pocket whose dorsal boundary is defined by a ridge (Plate 2F). Finger inner margins smooth (except for small granules present on lateral finger surfaces, especially near tips), gaping in males (Plate 2F), serrate, non-gaping (touching) in females; dactylus length approximately 1/2 propodus length ( Table 1 ). Propodus granular; proximal, dorsal surface with prominent brown propodal knob. Carpus anterior margin serrate with medial serrations becoming more developed as spines, or spines may be reduced to granulations (Plate 2D). Merus anterior margin dentate to serrate without crest, but smooth on lateral region (Plate 2D); dorsal surface granular.

Fifth pereopod (P5): Few setae present on ventral surface of P5 propodus, dactylus. P5 dactylus dorsal surface with 3 large, strongly curved spines near tip followed proximally by a row of approximately 5 shorter spines (Plate 7A); ventral surface with 5–6 discontinuous transverse rows of flattened chitinous spinules followed distally by 3–4 additional flattened chitinous spinules at ventral base of horny tip (Plate 8A). Propodus distal, ventral margin lined with several long chitinous spinules.

Male pleopods: Male first pleopods straight, distal 1/3–1/2 covered with setae.

PLATE 1. Tetralia metrics and some characters used in descriptions. A. carapace width (cw) and carapace length (cl) (freshly-collected female, Tetralia ocucaerulea , UF 9235, scale unavailable, photographed by G. Pauley); B. frontal margin (same specimen as in A.), arrows delineate notches (n); C. major left cheliped, median view, propodus length (pl) and dactylus length (dl) (preserved female, Tetralia brunalineata , LACM CR 2002-040.4); D. major right cheliped propodus (partial), carpus, and merus, dorsal view, arrows delineate propodal knob (pk) and crest (cr) (preserved male, Tetralia ocucaerulea , LACM CR 2002-040.13). All scale bars 1 mm.

LACM CR 2002-040.14 2.95 6.31 0.47 carapace carapace N/A

(female) damaged damaged Live coloration: Anterior dorsal half of carapace brown or pale orange (including anterior portion of eyestalks), posterior half white (Plate 2A); frontal margin orange-brown (may be faint), orbital, anterolateral margins dark brown. Ventral anterior region brown; dark line extending across posterior epistome margin; dark spots may cover entire ventral surface.

PLATE 2. Tetralia aurantistellata , new species (LACM CR 2002-044.2 freshly-collected male for image A; LACM CR 2002-043.1, holotype, preserved male for images B, D, F; MNHN B29229 preserved female for images C, E). A. whole body, dorsal view; B. frontal margin, dorsal view; C. left 3rd, 4th, and 5th pereopods, dorsal view, arrow indicates red spot on dactylus; D. major right cheliped carpus and merus, dorsal view, arrows indicate anterior margins; E. female tomentose pit (arrow) of major right cheliped; F. major right cheliped, dorsal/median view, left arrow indicates “elbow” and right arrow indicates gaping fingers. All scale bars 1mm.

Cheliped fingers orange with brown patch on proximal dorsal surface of dactylus in both sexes (Plate 2F); propodus, merus, carpus dorsal surfaces darker brown than ventral (Plate 2F); anterior margins of propodus, merus, carpus brown, orange or red, merus teeth white (Plate 2D); anterior margins of basi-ischium, coxa brown. Propodal knob dark brown.

Pereopods brown or tan, darker on dorsal surface than ventral surface; covered with uniform pattern of orange spots over all podomere surfaces and abdomen (Plate 2C); darker orange spots on dorsal surfaces of podomere articulations, red spot at dorsal base of dactylus horny tip (Plate 2C); dactylus tips white; large black spot absent at dorsal propodal-dactylar articulation on all pereopods.

Remarks. T. aurantistellata differs from the other described species of Tetralia in its overall color pattern, primarily by the presence of orange spots scattered over all pereopods and abdomen (Plate 2C). In addition to the unique color pattern, T. aurantistellata can be distinguished from other species of Tetralia by the following combination of morphological characters: (1) chelipeds markedly dissimilar in size (similar to that of Tetraloides species) (Plate 2A), (2) major cheliped fingers gaping in males (Plate 2F; see also T. brunalineata ), (3) cheliped merus crest absent (Plate 2D), (4) tomentose pit greatly reduced in males, and (5) medial frontal margin very finely denticulate, almost smooth, lateral frontal margins dentate (Plate 6A). T. aurantistellata may be mistaken for T. glaberrima (= T. fulva ), a known species that also features orange-red spots on the legs. However, the spots on T. glaberrima (= T. fulva ) are limited to the carpus, propodus and dactylus of the pereopods, the spots in T. aurantistellata cover all pereopod podomeres. In addition, spots are present on the abdomen of T. aurantistellata and absent on the abdomen of T.glaberrima (= T. fulva ).

Distribution. Tetralia aurantistellata has so far been identified from Philippine Is., Loyalty Islands and Fiji.

Etymology. From “aurantium” (Latin) for orange, “stella” (Latin) meaning star in reference to the presence of large star-like orange spots on the pereopods and abdomen.

Tables

TABLE 1. Morphometric data for the four new species of Tetralia.

Species	Dactylus length (mm)	Propodus length (mm)	Ratio of dacty- Carapace lus length to width propodus length (mm)	Carapace length (mm)	Ratio of carapace width to length
T. aurantistellata
ZRC R47 (female)	1.94	4.23	0.46 4.98	4.26	1.17
ZRC R47 (male)	2.98	5.35	0.56 5.08	4.34	1.17
LACM CR 2002-043.1 (male, holotype)	3.40	6.85	0.50 5.95	5.31	1.12
MNHN B29232 (female)	2.33	4.54	0.51 5.46	4.65	1.17
MNHN B29232 (female)	2.24	4.28	0.52 4.90	4.15	1.18
T. brengelae