Philarius rufus, Marin, Ivan & Anker, Arthur, 2011

Marin, Ivan & Anker, Arthur, 2011, A partial revision of the Philarius gerlachei (Nobili, 1905) species complex (Crustacea, Decapoda, Palaemonidae), with description of four new species, Zootaxa 2781, pp. 1-28 : 13-14

Philarius rufus n. sp.

( Figs. 10–14 , 19 A, B)

Type material. Holotype: ovigerous female, pcl 3.7 mm (QM W29052) Australia, Great Barrier Reef off S Queensland, Heron Island, sta. 98, 23.45322 S, 151.90045 E, outer reef, rubble, depth: 24–26 m, coll. S. McKeon, G. Cranich and others, 24.XI.2009 (fcn AUST 6115).

Description. Medium-sized pontoniine shrimp with subcylindrical body. Carapace smooth; antennal tooth sharp. Rostrum long, compressed, straight, with slightly ascendant tip overreaching distal margin of scaphocerite blade; dorsal lamina with five large dorsal teeth, four situated anterior to orbit (rostral teeth) and one situated slightly posterior to orbit (= postorbital tooth); most-distal portion of rostrum toothless; ventral margin with single tooth situated at about 0.6 length of rostrum; proximolateral rostral lamina without supraocular lobe. Pterygostomial angle slightly produced anteriorly, rounded.

Pleura of Abd1–5 rounded. Telson about three times as long as proximal width, narrowing distally, with two pairs of small dorsal submarginal spines situated at 0.5 and 0.8 of telson length, respectively; posterior margin armed with three pairs of spines, including one pair of short lateral spines, one pair of longer intermediate spines and one pair of median spines almost equal to intermediate spines.

Eyes as described for P. gerlachei .

Antennule with basal segment about 1.5 times as long as wide; distolateral angle with acute tooth; ventromesial tooth small, acute; intermediate and distal segments equal in length, as long as wide; proximal part of lateral antennular flagellum with 11 segments, accessory ramus with at least three visible segments. Antenna with basicerite bearing sharp distoventral tooth; scaphocerite relatively slender, about three times as long as maximal width, overreaching end of antennular peduncle, with well-developed, acute distolateral tooth, latter overreaching distal margin of blade.

Mouthparts typical for genus. Mxp2 with very narrow dactylus. Mxp3 relatively slender, with well-developed, slender exopod; lateral plate of coxa ear-shaped, curved distally; arthrobranch absent.

P1 smooth, relatively slender; ischium about 2.5 times as long as wide, with distally projecting blunt lobe; merus slender, about five times as long as wide; carpus slender, slightly longer than merus, about six times as long as wide, flaring distally, with several stout simple setae at carpo-propodal articulation; palm about 1.5 times as long as wide, subcylindrical; fingers stout, simple, tapering distally, about 2.5 times as long as wide, with straight cutting edges; fixed finger with one tuft of stiff plumose setae at mid-length of lateral margin.

P2 symmetrical in shape, slightly unequal in size, robust; surface of distal segments covered with simple setae; ischium about 2.5 times as long as wide; merus about 3.5 times as long as wide, with straight margins; carpus flaring distally, swollen mesially, with two blunt teeth distoventrally, rounded dorsally; palm subcylindrical, smooth, about three times as long as wide; fingers slender, about 1.5 times shorter than palm, about five times as long as wide; cutting edges with small triangular teeth along almost entire length; finger tips acute, simple, slightly curved.

P3–5 similar in general shape, robust; P3 with ischium, merus and carpus unarmed, covered with simple setae; propodus about five times as long as wide, with smooth margins, without setal tufts on distoventral margin, with one tuft of simple setae on distal margin; dactylus simple, stout, curved, distally acute.

Uropods moderately slender, slightly exceeding telson; distolateral tooth and spine subequal in length, moderately strong.

Colour pattern. Body semitransparent, pale orange-reddish, with minute red and white chromatophores forming bands (some half-moon shaped) on carapace and abdomen; two larger red spots present dorsally on second abdominal somite (within patch of white chromatophores); additional red spots present laterally on second and third pleurae; P1 and P3–5 uniform pale orange, with orange-red longitudinal line on each article; P2 pale orange, with some orange lines on merus and carpus, palm with small but conspicuous red spot proximally; fingers reddish; antennular and antennal flagella pale orange-yellow; corneas reddish ( Fig. 19 A, B).

Etymology. Name referring to the characteristic reddish colour pattern of the new species ( rufus = red or reddish-coloured in Latin); used as adjective.

Ecology. The single specimen was found among rubble (which possibly included pieces of Acropora ), at a depth of 24– 26 m.

Distribution. Presently known only from the type locality in Heron Island, Great Barrier Reef off southern Queensland, Australia.

Remarks. Philarius rufus n. sp. lacks supraorbital teeth and a well-marked tooth on the P2 carpus, and therefore, appears to be closely related to P. gerlachei , P. polynesicus n. sp. and the below-described P. m i n o r n. sp. and P. albimaculatus n. sp. However, P. r u f u s n. sp. can be separated from these four species by the slightly less depressed body and the absence of setal tufts on the distoventral margin of the P3 propodus (present in all other species). Philarius rufus n. sp. also differs from P. gerlachei and P. p o l y n e s i c u s n. sp. by the rostrum distinctly overreaching the scaphocerite blade and having a longer toothless terminal portion; and from these two species as well as P. m i n o r n. sp. by the post-orbital position of the most-posterior tooth on the dorsal lamina (vs. anteroorbital position of the most-posterior tooth in the other three species); and from P. albimaculatus n. sp., which is the only other species of the P. gerlachei complex with the most-posterior tooth of the dorsal lamina situated posterior to the orbit, by the presence of only four teeth on the rostrum, anterior to the orbit (vs. six in P. albimaculatus n. sp.). In life, P. r u f u s n. sp. can be separated from P. polynesicus n. sp., P. minor n. sp. and P. albimaculatus n. sp. by its characteristic reddish colour pattern ( Fig. 9 A, B); the background colour of other species is either pale greenish ( P. polynesicus n. sp., P. minor n. sp.) or semitransparent with white spots ( P. albimaculatus n. sp.) [see also Table 1].

Figures

FIGURE 9. Philarius polynesicus n. sp., paratype, ovigerous female from Moorea, French Polynesia (FLMNH UF Arthropoda 16159) [A – C]; holotype, male from Moorea (FLMNH UF Arthropoda 16148) [D, E]; colony of Acropora valida (Dana), host of P. polynesicus n. sp. in Moorea [F]. Photographs: A-E by A. Anker; F by G. Paulay.

FIGURE 10. Philarius rufus n. sp., holotype, ovigerous female from Heron Island, Australia (QM W 29052), lateral view. Scale bar = 2 mm.

FIGURE 11. Philarius rufus n. sp., holotype, ovigerous female from Heron Island, Australia (QM W 29052): A, anterior carapace, lateral view; B, frontal region, dorsal view; C, antennule, dorsal view; D, antenna, dorsal view; E, telson, dorsal view; F, distolateral margin of uropodal exopod, dorsal view; G, second maxilliped, lateral view; H, third maxilliped, lateral view.

FIGURE 12. Philarius rufus n. sp., holotype, ovigerous female from Heron Island, Australia (QM W 29052): A, first pereiopod, lateral view, B, same, chela, mesial view; C, second pereiopod, dorsal view; D, same, carpus, lateral view; E, same, chela, mesial view; F, third pereiopod, lateral view.

FIGURE 13. Philarius minor n. sp., paratype, female from Heron Island, Australia (FLMNH UF Arthropoda 24982), lateral view. Scale bar = 2 mm.

FIGURE 14. Philarius minor n. sp., paratypes, ovigerous female from Heron Island, Australia (FLMNH UF Arthropoda 24982) [A-C, E-H]; male from Heron Island, Australia (QM W 29051) [D]: A, B, D, anterior carapace, lateral view; C, frontal region, dorsal view; E, antennule, lateral view; F, scaphocerite, dorsal view; G, telson, dorsal view; H, sixth abdominal somite, telson and uropods, ventral view.

FIGURE 19. Colour patterns of three species of Philarius: A, B, Philarius rufus n. sp., holotype, ovigerous female from Heron Island, Australia (QM W 29052); C, D, Philarius minor n. sp., holotype, ovigerous female (C) and paratype male (D) from Heron Island, Australia (QM W 29050, W 29051); E, F, Philarius albimaculatus n. sp., holotype, male from Nosy-Bé, Madagascar (FLMNH UF Arthropoda 14472). Photographs: A-D by F, Michonneau; E, F by A. Anker.