Petalomera longipes Ihle, 1913

McLay, Colin L. & Ng, Peter K. L., 2007, Revision Of The Indo-West Pacific Sponge Crabs Of The Genus Petalomera Stimpson, 1858 (Decapoda: Brachyura: Dromiidae), Raffles Bulletin of Zoology 55 (1), pp. 107-120 : 113-116

Petalomera longipes Ihle, 1913

( Figs. 5–7 )

Petalomera longipes Ihle, 1913: 49 , Pl. 2, Fig. 12.

Petalomera pulchra – McLay, 1993: 166, Fig. 17a-b [not Petalomera pulchra Miers, 1884 ].

Material examined. – Indonesia: DUTCH EAST INDIES SIBOGA EXPEDITION 1899–1900 , stn 301, Rotti Island , 10 ° 38'S 123 ° 25.2'E, 18–45 m, 30 Jan.1900: 1 male 8.1 x 8.7 mm (holotype) (coll. M. Weber, De. 102.964) ( ZMC) . DANISH KEI ISLANDS EXPEDITION, 1922, stn 38, NE of Doe Roa , ~ 5º37'S 132º44'E, 35 m, 24 Apr.1922: 1 female (ovigerous), 12.9 x 14.4 mm (coll. T. Mortensen ); Stn 67, Java Sea , 5º48'S 106º12'E, 38 m, 27 Jul.1922: 1 female (ovigerous) 10.1 x 10.4 mm (coll. T. Mortensen ); Stn. 106 , 5º50'S 106º16'E, 32 m, 5 Aug.1922: 1 female 10.5 x 10.4 mm (coll. T. Mortensen) ( ZMC) . Philippines: MORTENSEN EXPEDITION 1914 , near Jolo , ~10ºS 121ºE, 46 m, 19.03.1914: 1 male 22.3 x 22.6 mm; Near Jolo, ~10ºS 121ºE, 37–55 m, 19 Mar.1914: 1 female 14.5 x 14.7 mm (coll. T. Mortensen) ( ZMC) . Chesterfield Islands : CHACAL 1: stn CP12 , 20º35.30'S, 158º47.40'E, 67 m, 23 Jul.1984: 1 male 20.8 x 22.5 mm; Stn DC43, 20º41.50'S 158º38.40'E, 78 m, 23 Jul.1984: 1 female 16.6 x 17.4 mm. ( MNHN) .

Type specimens. – The holotype ( ZMC De.102.964) is a male measuring 8.1 x 8.7 mm from Rotti Island , Indonesia .

Description. – Carapace long as or longer than wide, slightly convex, covered with small rounded granules, especially on anterior half of carapace, sparsely pubescent with a few longer setae fringing limbs. Frontal groove well marked, separating a pair of low rounded protuberances behind rostrum. Distinct crescent-shaped branchiocardiac grooves, with a central pit, joined by a shallow groove across mid-line. Cervical groove distinct, branchial groove less distinctly marked. Rostrum tridentate, all teeth serrated, horizontally directed, median tooth shorter, on a lower level, lateral teeth eave-like separated by U-shaped sinus.

Supraorbital margin concave behind lateral rostral tooth, entire edge granulate, interrupted by a distinct supraorbital tooth medially, followed by a notch, and margin ends at well marked orbital fissure beneath postorbital corner. A straight line connects tip of lateral rostral tooth and postorbital corner, running along anterior carapace margin. Suborbital margin convex, armed with a serrated tooth, visible dorsally. Hepatic area, between postorbital corner and beginning of anterolateral margin, has a few large granules, below level of suborbital margin with a granulated swelling, with a small tooth visible dorsally. Anterolateral margin begins at level of postorbital corner, armed with 2 granulated teeth: first is directed almost anteriorly, second behind cervical groove, directed more laterally. Behind both these teeth, carapace margin granulated; with 3 teeth (including small tooth below level of suborbital margin). Posterolateral tooth absent. Posterior carapace margin slightly convex, not granulated.

Suborbital area convex, granulated. Epistome triangular, flat, interantennular septum stout, margins granulated, interrupted by a notch midway along each lateral margin, beside first article of antennule. Corner of buccal frame with exhalant channels formed by corner of epistome and carapace margin, positioned immediately below base of antennae, adjacent to channel opening is a distinct granulated buccal tooth. Epimeral suture distinct. Inhalant channels at base of chelipeds densely setose. Rest of branchiostegal margin fits tightly around bases of pereopods.

First article of antennule longer than wide, sub-rectangular, second article inserted at disto-medial corner and folded laterally across distal end, article fits tightly against rostral extension that joins interantennular septum. Third article longer than wide, folds posteriorly and along with flagellum concealed beneath supraorbital edge. First article of antenna (urinal article) wider than long, beak-shaped medially, not gaping. Second article much longer than wide, distal border bears well developed bilobed exopod. Disto-medial corner produced as a curved, blunt lobe on which third article is inserted at an angle. Fourth article, like the third, as long as wide. All antennal articles freely moveable.

Third maxillipeds operculiform, surface with scattered coarse granules, palp exposed, margins of basis cannot meet in midline, crista dentata with 9 well developed sub-acute teeth with 7 or 8 calcareous teeth on the outer margin of basis.

Chelipeds well developed, larger in males. Merus trigonal in cross-section, lower margin granulated, inner surface petaloid, nacreous, fitting closely against subhepatic area of carapace. Outer surface of carpus convex, granulated, with 2 strong distal granules, inner margin of upper border with 5 or 6 granules. Outer face of propodus with granules that tend to be arranged in longitudinal rows. Inner margin of upper border crest-like, granulated. Fingers gaping, short, down-curved, hollowed out internally, so that teeth are on outer border. Edges of fingers armed with 7 or 8 well developed, distinct teeth, increasing in size distally, last 4 interlocking when fingers closed.

First 2 pairs of legs shorter than chelipeds, meri petaloid. Carpi tends to be flattened, fitting closely against preceding limbs, propodi sub-cylindrical. Dactyli as long as propodi, tips curved, inner margins armed with 4 or 5 short spines of similar sizes.

Last 2 pairs of legs reduced, third pair shortest, only last pair truly subdorsal in position. Dactylus of third pair opposed by a single, strong propodal spine. Dactylus of fourth pair also opposed by a single similar propodal spine, with another small spine on outer propodal margin at base of dactylus. Ratio of length along dorsal margin (not including spine) to width of propodus for third and fourth legs, 1.2 and 2.2, respectively.

Abdomen of 6 free segments, fourth or fifth segments widest in female, surface sparsely granulate. Uropod plates well developed and visible externally. Female telson much wider than long tip broadly rounded. All segments of male abdomen about the same width, granulated, uropod plates large, visible externally and used to lock the abdomen by fitting in front of prominent granulated flanges on coxae of first walking legs; such flanges absent in mature females. Male telson wider than long, tip truncate.

Both male gonopods in situ reach just beyond sternal suture 4/5. First gonopod composed of 2 articles: first article concave ventrally, to receive long extension of vas deferens, second article concave medially, gradually forming a short tube ending in a chitinous tip. Margins of both articles, and tip of second article, densely setose. Marginal setae of second article increases effective length of tube receiving second gonopod. Second gonopod composed of 3 articles: first short, cylindrical, second a shorter flattened and laterally expanded piece, and third is a long terminal part that starts out wide and flattened but narrows to horny needle-like structure, without microscopic structures on surface. Female spermathecal openings are at ends of sternal sutures 7/8, between bases of first walking legs; openings on elevations anterior to gonopores on coxae of second walking legs carried a small fragment of a compound ascidian that only covered the rear half of its carapace.

Distribution. – The male type came from Rotti Island, Indonesia, 10º38'S 123º25.2'E. The specimens reported here from the Philippine Islands, Jolo, ~10ºS, 121ºE, extend the known geographic range of P. longipes that now includes Indonesia, Philippine Islands and New Caledonia.

Figures

Fig. 5. Petalomera longipes Ihle, 1913, holotype male 8.1 x 8.7 mm (ZMC De.102.964): A, overall dorsal view; male 20.8 x 22.1 mm (CHALCAL 1, CP12); B, overall dorsal view; C, overall dorsal view, female 16.6 x 17.4, (CHALCAL 1, stn DC43).

Fig. 6. Petalomera longipes Ihle, 1913, holotype male 8.1 x 8.7 mm (ZMC De.102.964): A, detail of carapace tubercles right anterolateral area; male 20.8 x 22.1 mm (CHALCAL 1, CP12); B, detail of carapace tubercles right anterolateral area.

Fig. 7. Petalomera longipes Ihle, 1913: A–D, dorsal views of frontal and right anterolateral areas; E, outer view of left chela; F, ventral view of abdominal locking mechanism; G, propodus and dactyl right P4; H, propodus and dactyl right P5. A, B, holotype male 8.1 x 8.7 mm (ZMC De.102.964); C, D, male 20.8 x 22.1 mm (CHALCAL 1, CP12). Scale bars: A, B, G, H = 1 mm; C–F = 2 mm.