Hamopontonia physogyra, Marin, Ivan, 2012
Marin, Ivan, 2012, The “ Hamopontonia corallicola ” Bruce, 1970 species complex (Crustacea, Decapoda, Palaemonidae): new records and new species from the Great Barrier Reef, Australia, Zootaxa 3272, pp. 35-56: 46-55
treatment provided by
Hamopontonia physogyra sp. nov.
Material examined. Australia, GBR, Lizard Island area — Holotype, ovigerous female (pcl. 4.0 mm, tl. 15 mm), 1 male (pcl. 3.2 mm, tl. 15) (QM W 33509View Materials), 2 males (pcl. 3.2, 3.5 mm) (QM W 33521View Materials) — Lagoon, Channel, bommies and patch reef, LI 10 -001, 14 ° 41.317 ’S 145 ° 27.835 ’E, 10–12 meters, on Physogyra lichtensteini , coll. I. Marin, 26 Aug. 2010; 2 ovigerous females, dissected (pcl. 4.1, 3.8 mm), 2 males, dissected (pcl. 4.0, 2.7 mm) (QM W 33510View Materials) — Lagoon between Palfrey Island and southern patch reef, LI 10 -051, 14 ° 41.927 ’S 145 ° 27.007 ’E, 8 m, on Physogyra lichtensteini , coll. I. Marin, 0 1 Sept. 2010; 2 ovigerous female (pcl. 3.0, 2.8 mm), 5 males (pcl. 3.0, 2.5, 2.2, 2.2, 2.2 mm) (QM W 33511View Materials) — McGillivray Reef, wall, LI 10 -073, 14 ° 39.509 ’S 145 ° 29.561 ’E, 12–15 m, on Physogyra lichtensteini , coll. I. Marin, 0 4 Sept. 2010.
Description. Medium-sized pontoniine shrimp with cylindrical slightly depressed body. Carapace swollen and smooth, with large antennal tooth, without hepatic or supraorbital teeth ( Fig. 9View FIGURE 9 c –g). Rostrum long, slender, distally acute, compressed, reaching to distal margin of second antennular segment; rostral formula 2 + 4–5 /0 ( Fig. 9View FIGURE 9 c –g); dorsal rostral carina well developed reaching to distal third of the carapace length, with small dorsal teeth; ventral rostral carina poorly developed, unarmed; proximal lateral rostral lamina feebly developed ( Fig. 9View FIGURE 9 b). Orbit well developed, deep, unarmed; inferior orbital angle bluntly produced distally. Pterygostomial angle produced, bluntly rounded distally.
Abdominal somites smooth; pleura of abdominal somites I –V rounded ( Fig. 8View FIGURE 8). Telson ( Fig. 10View FIGURE 10 e –h) about 3 times as long as proximal width, narrow in central part, with 3 pairs of medium sized submarginal dorsal spines at 0.5, 0.7 and 0.85 of telson length; distal margin of telson armed with two hook-like projections (teeth) turned downward and distinct notch medially, notch covered with numerous simple setae ( Fig. 10View FIGURE 10 e –h).
Eyes ( Fig. 9View FIGURE 9 b) well developed, large; eyestalk smooth, cylindrical, about 1.5 times as long as wide; cornea well developed, large, subovate.
Antennula ( Fig. 10View FIGURE 10 a, b) well developed; basal segment relatively slender, about twice longer than wide, with well developed slender acute stylocerite, with distolateral angle bearing large acute triangular tooth and small medial lobe; ventromedial tooth small ( Fig. 10View FIGURE 10 b); intermediate segment stout, about 1.5 times as long as wide, with lateral margin slightly produced; distal segment stout, as long as wide, equal to previous segment; proximal part of upper antennular flagellum with 5 or 6 separate segments, shorter ramus with more than 15–20 segments; about 7 or 8 groups of aesthetascs present.
Antenna ( Fig. 10View FIGURE 10 c) well developed, basicerite about 1.5 times longer than wide, smooth, without distoventral tooth; scaphocerite wide, about 2.5 times longer than maximal width, overreaching antennular peduncle, distolateral tooth well developed, acute, not reaching to the distal margin of the blade.
Mouthparts characteristic for the genus and previously described species (see Bruce 1970, fig. 3 for H. corallicola ). Maxilliped III ( Fig. 10View FIGURE 10 d) with slender segments; ischiomeral segment about 4.5 times longer than wide, antepenultimate segment about 4 times as long as wide; penultimate segment slender, about 2.5 times as long as wide. Pereiopod I ( Fig. 11View FIGURE 11 a) with relatively slender segments; coxa as long as wide, with distoventral lobe; basis as long as wide; ischium about 3.5 times longer than wide; merus slender, about 3.5 times as long as wide; carpus about 5.5 times as long as wide, slightly shorter than carpus; propodus about 5.5 times longer than wide, about twice as long as chela, slightly flaring distally; palm ( Fig. 11View FIGURE 11 b) cylindrical, about 2.5 times longer than wide; fingers slender, about 4 times as long as wide, with straight, smooth cutting margins and simple tips ( Fig. 4View FIGURE 4 B).
Pereiopods II similar in shape and slightly unequal size ( Figs. 8View FIGURE 8). Major pereiopod II ( Fig. 11View FIGURE 11 c, d) with relatively robust and smooth segments; coxa as long as wide, with small distoventral lobe; basis as long as wide; ischium about 3.5 times longer than wide; merus robust, about 3 times longer than wide, with straight lateral margins; carpus triangular, stout, flaring distally, overlapping carpo-propodal articulation, with smooth distal margin ( Fig. 11View FIGURE 11 d); palm ( Fig. 11View FIGURE 11 d) cylindrical, smooth, about 5 times as long as wide, slightly swollen in central region; fingers robust, about 3.5 times shorter than palm; fixed finger (pollex) ( Fig. 11View FIGURE 11 e) relatively stout, compressed laterally, about 2.5 times longer than wide, with two medial teeth and simple sharp curved tip, with small medial depression opposite to tooth on movable finger; movable finger (dactylus) stout, compressed, with large tooth situated on proximal third of cutting margin, with simple curved tip. Minor pereiopod II generally similar in proportions and structure to the major pereiopod II; about 1.5 times smaller in size than major pereiopod II ( Fig. 11View FIGURE 11 f –h).
Pereiopod III with smooth slender unarmed segments ( Fig. 11View FIGURE 11 i); coxal segment as long as wide, unarmed; basis as long as wide; ischium robust, about 2.5 times longer than wide; merus slender, about 4.5 times as long as wide; carpus about 2.5 times longer than wide, about half of length of propodus and merus; propodus relatively slender, about 5.5 times as long as proximal width, with smooth unarmed margins, without ventral or distoventral teeth; dactylus simple, with basal part about 1.5 times as long as wide, with simple slender, curved unguis ( Fig. 11View FIGURE 11 j). Pereiopods III –V similar.
Pleopods normal, without specific features. Uropods slender, slightly exceeding telson; distolateral margin of uropodal exopod rectangular with small movable distolateral spine, fixed tooth absent.
Males are morphologically similar to female, but smaller in size, with better developed and unequal pereiopods II ( Fig. 8View FIGURE 8 b, 12).
Differential diagnosis. The new species is mostly related and morphologically similar to Hamopontonia corallicola Bruce, 1970 . Both species clearly differ from H. fungicola sp. by unequal pereiopods II (vs. equal in H. fungicola ). From H. corallicola the new species can be mainly separated by deeper dorsal rostral carina (see Fig. 9View FIGURE 9), different coloration (see below) and association with the different coral host. Additional minor morphological differences between H. corallicola and the new species are: 1) more slender chelipeds in H. corallicola than in H. physogyra sp. nov., especially in males (see Figs. 1View FIGURE 1, 8View FIGURE 8) and 2) stouter fingers of pereiopods II in H. physogyra sp. nov. (see Figs. 1View FIGURE 1 f, g; 11 e, h).
Coloration. Females. Generally body and appendages transparent; cornea brightly white, eyestalk transparent; antennula and antenna transparent fringed with white and small blue dots; carapace with large dorsal patch consisting of small white dots in the centre fringed with broad white band; similar dorsal patch situated on dorsal margin of abdominal somites III, pleura and ventral margins of abdominal somites III with large white markings; pleura of others abdominal somites with numerous small blue and white dots; telson and uropods transparent, fringed with blue and white dots; chelipeds and ambulatory pereiopods generally transparent covered with numerous white and blue dots. Coloration of the specimens also varies from specimens with well marked large dorsal patches ( Fig. 13View FIGURE 13 A, B) to mostly transparent specimens ( Fig. 13View FIGURE 13 E, F); in some specimens ( Fig. 13View FIGURE 13 C, D) only a single dorsal patch on carapace presents.
Coloration of males is generally similar to coloration of females. Body and appendages transparent; cornea brightly white, eyestalk transparent; antennula, antenna, appendages and telson transparent fringed with white and blue small dots; carapace with large dorsal patch consisting of small white dots in the centre fringed with broad white band; similar dorsal patch situated on dorsal margin of abdominal somites III ( Fig. 13View FIGURE 13 G); immature individuals ( Fig. 13View FIGURE 13 H) completely transparent with small white and blue dots on body and appendages.
The new species clearly differs from congeners by its unique coloration having 1) body and appendages covered with numerous white and blue dots (vs. covered with white broad bands and tiny reds dots in H. corallicola and generally transparent covered with tiny red dots in H. fungicola sp. nov.); 2) coloration of dorsal patches consisting of small white spots forming a kind of ornamentation in the centre of the patch fringed with broad white or creamy band (vs. dorsal patches red or orange in the centre fringed with white band in H. corallicola and uniformly white or creamy in H. fungicola sp. nov.) and 3) by telson and uropods generally transparent fringed with a row of small white and blue dots (vs. completely transparent in H. corallicola and H. fungicola sp. nov.). From H. corallicola the new species also differs by the absence of white spots behind the orbits of carapace. The presence of these white lateral spots on carapace is characteristic only for H. corallicola .
Measurements. The largest collected ovigerous female has pcl. 4.0 mm, tl. 15 mm; the largest male — pcl. 3.2 mm, tl. 15.
Host. The species was found exclusively in association with caryophyllid grape bubble coral Physogyra lichtensteini Milne-Edwards & Haime, 1851 (Hexacorallia, Scleractinia , Caryophyllidae ) ( Fig. 15View FIGURE 15 C). The other species found inhabiting the same host is Vir smiti Fransen & Holthuis, 2007 ( Marin & Caley 2011) but both species have never been seen inhabiting the same host together.
Etymology. The species is named after its association with caryophyllid coral of the genus Physogyra Quelch, 1884 (Hexacorallia, Scleractinia , Caryophyllidae ), P. lichtensteini Milne-Edwards & Haime, 1851 .
Distribution. Presently known from its type locality, Lizard Island, the Great Barrier Reef of Australia only.
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