Philarius condi, Marin, Ivan, 2012

Marin, Ivan, 2012, A new species of pontoniine shrimp genus Philarius Holthuis, 1952 (Crustacea: Decapoda: Palaemonidae) from the Great Barrier Reef of Australia, Zootaxa 3182, pp. 43-50 : 44-50

Philarius condi sp. nov.

( Figs. 1–4, 4 A–F, 5A–D)

Material examined. Holotype, male (pcl. 3.8 mm, tl. 12.5 mm) (QM W33514)— Australia, GBR, Lizard Island area, Day Reef, back reef, st. LI10–080, 14º28.331’S 145º31.153’E, depth 0.5 m, on Acropora monticulosa , coll. I. Marin, 0 5 Sept. 2010; allotype, ovigerous female, dissected (pcl. 4.4 mm, tl. 15 mm) (QM W33512)—from the same host.

Paratypes. 1 ovigerous female (pcl. 4.0 mm), 1 male (pcl. 2.4 mm) (QM W33515)—Day Reef, back reef, LI10–080, 14º28.331’S 145º31.153’E, depth 0.5 m, on Acropora gemmifera , coll. I. Marin, 0 5 Sept. 2010; 1 ovigerous female (pcl. 3.2 mm), 1 male (pcl. 3.0 mm) (QM W33516)—Yonge Reef, back reef, st. LI10–124, 14º34.277’S 145º37.180’E, depth 1 m, on Acropora monticulosa , coll. I. Marin, 10 Sept. 2010.

Description. Allotype female (QM W33512). Medium - sized shrimp with subcylindrical body ( Fig. 1 ). Carapace swollen, smooth, with well developed sharp antennal tooth ( Fig. 2 B). Rostrum long, compressed, slightly turned upward, with well developed dorsal lamina armed with 4 large dorsal teeth; ventral margin with well developed lamina bearing one ventral tooth on the level of most distal dorsal tooth; proximal lateral rostral lamina well developed, convex, without supraocular tubercle ( Fig. 2 A). Orbit well developed. Pterygostomial angle bluntly produced.

Abdominal somites smooth; pleurae of abdominal somites I–V rounded. Telson ( Fig. 2 C) about 1.7 times as long as proximal width, narrowing distally, with 2 pairs of small dorsal submarginal spines at 0.5 and 0.75 of telson length; distal margin of the telson armed with 3 pairs of spines including 1 pair of short stout lateral spines, 1 pair of long slender intermediate spines and 1 pair of simple medial spines about twice shorter than intermediate spines.

Eyes ( Fig. 2 B) well developed, large and stout, with subovate cornea; eyestalk about as long as wide; cornea oval; well marked accessory pigment spot presents posterodorsally.

Antennula ( Fig. 2 D) well developed; basal segment about as long as wide, with well developed stylocerite; with distolateral angle bearing large acute triangular tooth reaching to the middle of distal antennular segment, without medial convex projection (lobe); submarginal ventral tooth distinct, small, situated near medial border of basal segment; intermediate segment stout, as slightly wider than long; distal segment stout, as long as wide; proximal part of upper antennular flagellum with 10–12 separate segments, shorter ramus with 4–5 segments.

Antenna well developed, basicerite with sharp triangular distoventral tooth, overreaching distal margin of the segment; scaphocerite ( Fig. 2 E) wide, about twice longer than maximal width, greatly overreaching intermediate antennular segment, distolateral tooth well developed, acute, overreaching distal margin of the blade.

Mouthparts characteristic for the genus and previously described species (e.g. Marin & Anker, 2011), without specific features.

Pereiopod I normal, segments unarmed; coxal segment with well developed curved lobe distoventrally; basis as long as wide; ischium about twice as long as wide, with distal projected blunt lobe; merus slender, about 4 times as long as wide; carpus slender, slightly longer than merus, about 4.5 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; dactylus and fixed finger (polex) stout, simple, tapering distally, about 3 times as long as wide, with entire cutting edges; fixed finger with a bunch of stout strong plumose setae at the middle of its lateral margin.

Pereiopods II equal in shape and slightly dissimilar in size; with relatively robust segments ( Figs. 1 , 3 ); coxal segment with well developed curved lobe distoventrally; ischium about 1.7 times longer than wide; merus about 3 times as long as wide, with slightly convex dorsal and straight ventral margins; carpus flaring distally, swollen in medial part, distal margin with 2 blunt projections ventrally and rounded margin dorsally ( Fig. 3 B); palm ( Fig. 3 B, D) cylindrical, swollen proximally, about 2.5 times as long as wide, with straight margins; fingers slender, about as long as the length of palm, about 5 times longer than wide, with straight cutting edges bearing small triangular teeth along its length, with acute, simple and curved tips.

Pereiopod III ( Fig. 3 E) robust, with unarmed segments covered with small simple setae; propodus relatively stout, about 4.5 times as long as wide, with smooth straight lateral margins, with 4–5 bunches of long simple setae distoventrally and a tuft of long simple setae distally; dactylus strong, simple and curved. Pereiopods III–V similar; pereiopod V with setal braches on distal part of propodus.

Pleopods normal, without specific features. Uropods ( Fig. 2 C) stout, exceeding telson; distolateral margin of exopod with triangular fixed tooth and movable spine.

Male holotype morphologically similar to described female allotype, slightly smaller in size. Rostral formula— 4/1. Pereiopods II almost equal in shape and size, larger than in females; palm ( Fig. 3 A) cylindrical, swollen proximally, about twice longer than wide; fingers ( Fig. 3 C) slender, about as long as the length of palm, about 6 times longer than wide.

Coloration. Body semitransparent, with violet-blue longitudinal stripes along appendages; dorsal margin of eyestalk, inner margin of antennular segments and flagella, antennal flagella violet-blue; abdominal pleurae with blue stripes; gonads and eggs greenish-white ( Fig. 4 A–F). Distal segments of pereiopods II (chelipeds) generally yellowish in large specimens.

Differential diagnosis. The new species clearly belongs to “ Philarius gerlachei ” species complex recently revised by Marin & Anker (2010). Within the complex the new species is mostly morphologically similar to Philarius polynesicus Marin & Anker, 2010 , and can be clearly separated from the latter species by one stable morphological feature only—longer fingers of pereiopod II, especially in males ( Fig. 4 F, H)—fingers are equal to palm length in both males and females in P. condi sp. nov. ( Figs. 3 A, B; 4E, F); fingers of pereiopods II slightly shorter in females and about twice shorter then palm in males of P. polynesicus ( Fig. 4 G, H; see Marin & Anker, 2010). At the same time, both species can be easily separated by coloration—longitudinal stripes on appendages, especially pereiopods, are violet-blue and more bright in P. condi sp. nov. ( Fig. 4 A–F) while stripes are whitish-green and feebly marked in P. polynesicus ( Fig. 4 G–H). Both species inhabit different hosts and ecological niches within coral reef ecosystems: P. condi sp. nov. is associated with shallow-dwelling stout-branched species of the genus Acropora Oken, 1815 ( Scleractinia , Acroporidae ), such as A. gemmifera (Brook, 1892) and A. monticulosa (Brüggemann, 1879) , living in high energy ecosystems of reef slopes influenced by strong waves while P. polynesicus is associated with slender - branched species of the genus Acropora , for example, A. valida (Dana, 1842) , living in protected habitats of the coral reef ecosystems such as back reef and lagoon. For the difference from the remained species of the genus see key presented by Marin & Anker (2010; all morphological features are similar to P. polynesicus except presented above).

Hosts and ecology. Philarius condi sp. nov. is found in a narrow ecological niche within the coral reef ecosystem. The species lives at the base of stout conoid branches of Acropora gemmifera and A. monticulosa , living on slopes of outer reefs and large coral boulders influenced by strong waves, so called “high energy reef ecosystems” ( Fig. 5 ). These host coral species are mostly specific for such environments having strong stout conoid branches, which can stand the influenced of strong waves. The new shrimp species was found exclusively inhabiting hosts living in a shallow part of observed slopes, not deeper than 1–1.5 meters; all observed deeper-dwelling colonies of the same hosts were occupied by larger pontoniine species of the genus Harpilius Dana, 1852 , H. consobrinus De Man, 1902 . By one of author’s hypothesis, being larger the latter species drive away smaller P. c o n d i sp. nov. from deeper dwelling hosts but the ecological niche of H. consobrinus is limited by the influence of strong waves in upper 1.5 meter depth where this large species is possibly washing out from the colony. Specimens of Philarius condi sp. nov. were never observed inhabiting the same host with specimens of Harpilius consobrinus .

Distribution. The species is known from the type locality only, Lizard Island, the Great Barrier Reef of Australia.

Etymology. The species is named after Condo Costello (AIMS), who greatly helped during the collecting of described specimens.

Figures

FIGURE 1. Philarius condi sp. nov., A—allotype, ovigerous female (QM W 33512); B—holotype, male (QM W 33514), dorsal views.

FIGURE 2. Philarius condi sp. nov., allotype, ovigerous female (QM W 33512): A—front of carapace, dorsal view; B—front of carapace and rostrum, lateral view; C—telson and uropods; D—antennula; E—scaphocerite of antenna.

FIGURE 3. Philarius condi sp. nov., holotype, male (QM W 33514) (A, C); allotype, ovigerous female (QM W 33512) (B, D, E): A—left major pereiopod II; B—right major pereiopod II; C—fingers of right major pereiopod II; D—chela of left pereiopod II; E—left pereiopod III.

FIGURE 4. Coloration of alive specimens. Philarius condi sp. nov.: A, E—allotype, female (QM W 33512); B—holotype, male (QM W 33514); C, D—paratype, ovigerous female (QM W 33516); F—paratype, male (QM W 33515). Philarius polynesicus Marin & Anker, 2010: G—paratype ovigerous female (FLMNH UF Arthropoda 16159); H—holotype male (FLMNH UF Arthropoda 16148) from Moorea, French Polynesia (copied from Marin & Anker, 2010).

FIGURE 5. Philarius condi sp. nov. at the base of branches of its host, A. monticulosa (A – D), (arrows); E – F— Acropora monticulosa on the slope of coral boulder, depth 1 meter; G— Acropora gemmifera; H— Philarius condi sp. nov. (arrow) at the base of branches of A. gemmifera.