Laomenes ceratophthalmus Borradaile 1915
Creators: name: Marin, Ivan
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Palaemonidae
Laomenes
Laomenes ceratophthalmus

description: Laomenes ceratophthalmus (Borradaile, 1915)
(Figs. 25–29, 33 A, C, E)
Periclimenes ceratophthalmus Borradaile 1915: 211 [type locality: Malé Atoll, Maldive Islands]; 1917: 324, 365, pl. 54; fig. 9. — Holthuis 1952: 56, fig. 20. — Bruce 1974: 192 –193, fig. 2; 1983: 880, figs. 4A–D, 5, 6A–C, 7F. Laomenes ceratophthalmus.— Okuno & Fujita 2007: 119 [excluding ovigerous female (CMNH–ZC 02071) described on Fig. 2].
Material. Vietnam. Nhatrang Bay: 1 males (pcl. 2.5, 2.5 mm) (ZMMU); 1 ovigerous female (pcl. 3.5 mm), 1 male (pcl. 2.2 mm) (ZMMU), Mun Island, 15–20 m, on crinoid Himerometra robustipinna, 18.vi.2006, coll. I. Marin; 1 ovigerous female (pcl. 3.5 mm), 1 male (pcl. 2.5 mm) (ZMMU), Mun Island, 15–20 m, 26.vi.2006, coll. I. Marin; 1 ovigerous female (pcl. 3.5 mm), 1 male (pcl. 2.2 mm), 1 juv. (2.0 mm) (ZMMU), Dun Island, 15–20 m, on crinoid Himerometra robustipinna, 20.vi.2006, coll. I. Marin; 1 ovigerous female (pcl. 3.5 mm), 1 male (pcl. 2.2 mm), 4 juv (pcl. 1.6, 1.8, 2.0, 2.1 mm) (ZMMU), Dun Island, 20 m, on crinoid Himerometra robustipinna, 20.vi.2006, coll. I. Marin.
Diagnosis. Carapace swollen, smooth, with antennal and hepatic teeth (Fig. 26 A); hepatic tooth triangular, larger than antennal. Rostrum long, slender and straight, tapering distally, with 3 or 4 dorsal teeth in the distal third of dorsal carina, ventral teeth absent. Lateral rostral lamina forming conspicuous supraocular teeth in proximal part (Fig. 26 B). Orbit well developed; inferior orbital margin produced, rounded. Abdominal somites smooth; pleura of abdominal I–V somites rounded ventrally (Fig. 25). Telson about 3 times longer than wide in proximal part (Fig. 26 I), narrowing posteriorly, with 2 pairs of small submarginal dorsal spines at 0.55 and 0.75 of telson length. Eyes large (Fig. 26 C); eyestalk stout, as long as wide, with ovate cornea bearing large blunt apical papilla. Antennule well developed (Fig. 26 D); distolateral margin of basal antennular segment with acute distolateral tooth and well marked rounded medial projection (Fig. 26 E, F), submarginal ventral tooth small, situated near medial border of basal segment. Mandible robust (Fig. 28 A, B), without palp; incisor process broad, with 7 terminal teeth (Fig. 28 C); molar process well developed, robust, with several teeth distally. Maxillule (Fig. 28 D) normal, with well developed bilobed palp; upper lacinia slightly curved, flaring distally, with strong setae distally; lower lacinia robust, flaring distally. Pereiopod I (Fig. 29 A) slender, carpus without distolateral setae at carpo-propodal articulation; dactylus and fixed finger robust with numerous terminal setae, cutting edge entire, tips not spatulated (Fig. 29 B). Pereiopod II equal in size and shape, with robust segments (Fig. 29 C); carpus flared distally, as long as maximal width, with distinct ventrolateral notch (Fig. 29 D, E); palm cylindrical; fingers slender, with entire cutting edges bearing 7 distinct triangular teeth; with curved tips (Fig. 29 F). Pereiopod III (Fig. 29 G) slender, segments unarmed; propodus without distoventral spines, with row of long plumose setae distally; dactylus robust (Fig. 29 H), as long as maximal width, with long, acute and curved unguis; accessory tooth small, turned down, situates at the middle of dactylus, accompanied with tuft of long slender setae. Uropodal exopod with single mobile spine distolaterally (Fig. 26 J).
Remarks. The current specimens are similar to the holotype described by Borradaile (1915) and partly redescribed by Bruce (1978). Despite the holotype possibly being juvenile, it is possible to recognize such diagnostic features as short eyestalk which is about as long as wide, with moderately produced apical corneal papilla (Borradaile 1917, Fig. 9 a, b). The rostrum of our specimens bears 3 or 4 dorsal teeth and is toothless ventrally (Fig. 26 A, 27A, C, E) similar to most references to this species (Holthuis 1952; Miyake & Fujino 1968; Bruce 1974, 1983). The rostrum of the type specimen “ bearing above four teeth, all in its distal half ”; the figure (Fig. 2 b in Borradaile 1917) shows a slender rostrum with the position of the posterior tooth close to the mid-length of the rostrum similarly to one of the juvenile specimens presented in our collection (see Fig. 27 E).
As indicated above, Laomenes ceratophthalmus was previously misidentified with Laomenes tigris sp. nov. Both species share a rostrum with dorsal teeth situated in its distal part and ventrally toothless. Nevertheless, these species can be clearly distinguished by the form of the eyes (eyestalk of L. ceratophthalmus (see Bruce 1978, Fig. 2 A; this paper, Fig. 26 C) is significantly shorter than in L. tigris sp. nov. (Kemp 1925, Fig. a; this paper, Fig. 20 D)), by the presence of dorsal teeth posterior the mid-length of rostrum in L. tigris sp. nov. (vs. all dorsal teeth situated anterior to mid-length of rostrum in L. ceratophthalmus). The propodus of pereiopod III in L. tigris sp. nov. possesses about a dozen rows of simple setae along the distoventral margin (Kemp 1925; this paper) while only single distal row setae present in L. ceratophthalmus. The distolateral margin of the uropodal exopod in mature specimens of L. ceratophthalmus shows only a mobile spine, whilst the distolateral margin of the exopod in L. tigris sp. nov. bears a well-marked fixed tooth and a mobile spine. Further, a tiny fixed tooth on distolateral margin of exopod of uropod can be found in juvenile specimens of L. ceratophthalmus. It is most likely that the specimen described by Okuno & Fujita (2006, fig. 2) belongs to Laomenes tigris sp. nov. as the eyestalk is significantly longer that in true L. ceratophthalmus (Borradaile 1917, Fig. 2 a; Bruce 1978, fig. 2A; present paper, Fig. 26 C).
Coloration. General coloration of the body and appendages is red (Fig. 33 A, C, E); carapace with 2 dark red longitudinal bands dorsally, with 3 additional dark red longitudinal bands continuing to abdomen dorsolaterally and laterally.
Host. All specimens were collected exclusively from himerometrid crinoids Himerometra robustipinna (Carpenter, 1881) (Crinoidea: Himerometridae) (Fig. 34 A). Other species of crinoids elsewhere observed as hosts of this species are Dichrometra afra A. H. Clark, 1912 (Himerometridae), Lamprometra klunzingeri (Hartlaub, 1890), Stephanometra indica (Smith, 1876) and S. spicata (Carpenter, 1881) (Mariametridae) (see Bruce, 1981, 1982, 1983), but it is possible that these records refer to similar undescribed species. Equally, records from the family Mariametridae most likely refer to Laomenes tigris sp. nov.
Distribution. Widely distributed in Indo-West Pacific. Known from Kenya, Zanzibar, the Seychelles, Maldive Islands, Indonesia, Vietnam, the Great Barrier Reef of Australia, Papua New Guinea, the Palau Islands, Solomon Islands and Japan.
description: Published as part of Marin, Ivan, 2009, Crinoid-associated shrimps of the genus Laomenes A. H. Clark, 1919 (Caridea: Palaemonidae: Pontoniinae): new species and probable diversity, pp. 1-49 in Zootaxa 1971 on pages 33-39, DOI: 10.5281/zenodo.185020