Periclimenes iridescens Lebour 1949
Creators: name: Fransen, Charles H. J. M.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Palaemonidae
Periclimenes
Periclimenes iridescens

description: Periclimenes aff. iridescens Lebour, 1949
(Figs. 55–61)
? Periclimenes iridescens — Criales 1980: 73 (Bonaire, Curaçao).
Material examined. Bonaire: RMNH. CRUS.D.57893: 4 ovigerous females, pocl. 1.6–1.8 mm, 1 male, pocl. 1.4 mm, 1 juvenile pocl. 1.1 mm, stn BON.26, Small Wall, 12°10.685′N 068°17.539′W, 3.xi.2019, depth 42 m, scuba diving, on tuft of algae on encrusting Millepora with Nemaster grandis, collected by C.H.J.M. Fransen.
Description. Small sized, rather slender shrimp, with slender pereiopods (Fig. 55A). Carapace smooth. Rostrum (Fig. 55A–G) well developed, reaching to end of basal segment of antennular peduncle; lamina moderately deep, lateral carina indistinct, situated near to proximally slightly convex ventral margin with or without one small subdistal tooth; convex posterior part of ventral margin with single row of plumose setae proximally; dorsal margin convex, elevated, strongly compressed, with 5–6 subequal teeth, posteriormost tooth slightly more distant from distal teeth than distance between distal teeth, situated well behind posterior margin of orbit; few plumose setae just in front of dorsal teeth. Supra-orbital spines absent. Inferior orbital angle well developed, produced, rounded in lateral view. Antennal spine small, submarginal, situated below inferior orbital angle. Hepatic spine distinctly larger than antennal spine, situated well behind level of posterior orbital margin and slightly below level of antennal spine. Anterolateral angle of carapace (Fig. 55B) bluntly rounded, not produced.
Pleon (Fig. 55A) smooth. Third pleonite not produced posterodorsally. Pleura all broadly rounded. Sixth abdominal pleonite twice as long as fifth, posteroventral angle feebly produced, rounded, posterolateral angle acute.
Telson (Fig. 56A–C) 0.85 times as long as sixth pleonite and 3.9 times longer than anterior width; lateral margins converge posteriorly; two pairs of small sized submarginal dorsal cuspidate setae present at 0.50 and 0.75 of telson length; posterior margin 0.43 of anterior width, with median acute process, with three pairs of spiniform setae; lateral pair short, slightly shorter than dorsal cuspidate setae; intermediate spiniform setae well developed, about 0.19 of telson length, 2.0 times length of submedian spiniform setae.
Eyes (Fig. 55B, C) well developed; cornea globular, with distinct accessory pigment spot dorsolaterally; eyestalks twice as long as proximal width.
Antennular peduncle (Fig. 55B, C) exceeding tip of rostrum by distal two segments; proximal segment long, slender, 2.7 times longer than wide; lateral margin slightly convex, anterolateral margin produced, with strong distolateral tooth and row of setae; medial ventral margin with tooth; stylocerite slender, acute, almost reaching to middle of segment; statocyst containing granular statolith; intermediate and distal segments short, together equal to 0.5 of proximal segment length; upper outer flagellum biramous, with first 4 segments fused; aesthetascs present on distal 4 segments of fused part and short free ramus; shorter free ramus two-segmented, longer rami with about 9 segments; lower inner flagellum slender, about as long as upper flagellum.
Antennal basicerite (Fig. 55B) with lateral tooth; ischiocerite and merocerite normal; carpocerite slender, reaching 0.4 of length of scaphocerite; scaphocerite long, rather slender, with lamella overreaching distal margin of antennular peduncle; lateral border straight, ending in acute large distolateral tooth; lamella extending beyond distolateral tooth, feebly angulated distomedially, about 3.3 times longer than wide, with greatest width at about half of its length.
Epistome and labrum normal.
Second and third thoracic sternites unarmed. Fourth thoracic sternite without medial process, with shallow lateral carinae posteromedial of first pereiopods.
Fifth thoracic sternite with shallow lateral plates posteromedial of second pereiopods.
Sixth to eighth thoracic sternites unarmed.
Mandible (Fig. 56D, E) with cylindrical molar process bearing a few brushes of setae distally; incisor process slender, with four well developed teeth distally of right mandible, of which lateralmost and medialmost teeth slightly enlarged, with two small denticles subdistally on medial margin; left mandible with incisor process with five well developed teeth distally of which lateralmost and medialmost teeth enlarged; without palp.
Maxillula (Fig. 56F) with upper lacinia subrectangular with row of few spines and serrulate setae medially; lower lacinia slenderer, with few serrulate setae distally; palp bilobed, medial lobe with single short recurved simple seta.
Maxilla (Fig. 56G) with short tapering non-setose palp with few plumose setae laterally; basal endite well developed, distinctly bilobed, with minutely serrulate setae medially; coxal endite obsolete, median margin convex, without setae; scaphognathite normal, widest centrally, about 2.8 times longer than broad, with marginal plumose setae.
First maxilliped (Fig. 56H) with short, slender, tapering palp without setae; basal region broad, not distinctly separated from the coxal region; median margin of coxa and basis provided with setulose and slender simple setae; caridean lobe distinct, with coarsely setulose plumose marginal setae; flagellum of exopod well developed with 4 long plumose distal setae and few short subdistal setae; epipod rounded.
Second maxilliped (Fig. 57A) with dactylar segment narrow, 3.1 times longer than wide, straight medially, densely fringed with numerous coarsely serrulate, spiniform, and long curled, finely serrulate setae medially; propodal segment longer than dactylar segment, almost twice as long as wide, distomedial margin rounded, with few long serrulate and simple setae; carpus short, unarmed; meral segment short, not excavate; ischium excavate, fused to basis; basis with long slender exopod exceeding length of endopod, with 4 long plumose setae distally; coxa slightly produced medially, with rounded small oblong epipod laterally.
Third maxilliped (Fig. 57B) slender; terminal segment 4.5 times longer than proximal width, slightly shorter than length of penultimate segment, with few serrulate and simple setae medially; penultimate segment slender, 4.7 times longer than wide; meral and ischial segments fused, 1.5 times longer than penultimate segment, with long setae along medial margin; basal segment short, medial margin convex with few long setae; exopod reaching 0.7 of ischiomeral segment, with 4 plumose setae distally; coxa slightly produced medially, with rounded lateral plate, without arthrobranch.
First pereiopod (Fig. 57C) slender, almost reaching distal margin of scaphocerite; chela with palm subcylindrical, straight, twice as long as wide; fingers almost as long as palm, straight not subspatulate, with brushes of few setae in distal part, cutting edges entire, tips of fingers hooked; carpo-propodal brush well developed; carpus 1.1 times length of chela, 3.75 times longer than distal width; merus slightly longer than carpus, about twice length of ischium; ischium with few long simple setae medially; basis short, with few long simple setae medially; coxa with small medial protuberance with long simple seta.
Second pereiopods, subequal in length, dissimilar. Major second pereiopod (Fig. 58A) extending beyond antennular peduncle with chela; chela with palm subcylindrical, straight; palm about 4.4 times as long as wide; fingers (Fig. 58B–D) 0.46 of palm length, very slightly gaping centrally; dactylus about as wide as fixed finger, with distinct dorsolateral longitudinal carina, with brushes of setae in distal part, unguis strongly hooked, cutting edge with one triangular tooth proximally; fixed finger with tip strongly hooked, cutting edge with one triangular tooth in proximal half, at same level of tooth on cutting edge of dactylus; carpus, merus and ischium unarmed, their length ratios of 0.55, 0.80, and 0.88 times length of palm; basis and coxa without special features. Minor second pereiopod (Fig. 59A), similar but more slender than major pereiopod; chela with palm subcylindrical, straight; palm about 3.7 times as long as wide; fingers (Fig. 59B, C) 0.85 times as long as subcylindrical palm, slender, cutting edges not gaping, entire; dactylus without dorsolateral longitudinal carina; carpus, merus and ischium unarmed, their length ratios of 1.8, 1.3, and 1.5 times length of palm; basis and coxa without special features.
Ambulatory pereiopods (Fig. 60A, C, E) slender, similar in form, slightly increasing in length from third to fifth; dactylus (Fig. 60B) of third pereiopod slender, uniformly tapering, about 0.23 of propodus length, 4.4 times as long as proximal width, with slender unguis 0.65 times as long as corpus, with short accessory tooth, 0.22 times unguis length; propodus about 12 times longer than wide, with two distoventral serrulate spiniform setae and few simple spiniform seta subdistally on ventral border, with few plumose and simple setae distally on dorsal margin; carpus, merus and ischium 0.41, 0.88, and 0.48 of propodus length, unarmed; basis and coxa without special features; fourth pereiopod (Fig. 60C, D) similar, with row of one pair of serrulate spiniform setae, one single serrulate spiniform seta, and one simple spiniform seta on distoventral margin of propodus; fifth pereiopod (Fig. 60E, F) with row of two pairs of serrulate spiniform setae and one single serrulate spiniform seta on distroventral margin of propodus.
Endopod of first pleopod in ovigerous female (Fig. 61C) short, 0.26 of length of exopod, with long plumose setae along its entire margin. Endopod of first pleopod in male (Fig. 61A) short, 0.47 times length of exopod, distally rounded, with 3 plumose setae along lateral margin and one long plumose seta in proximal part of medial margin with three small short setae somewhat more anteriorly. Endopod of second pleopod in male (Fig. 61B), 0.90 times length of exopod. Appendix masculina almost as long as appendix interna, with four long setae (sub)distally.
Uropods (Fig. 55A) extending beyond tip of telson; protopodite unarmed laterally; exopod with lateral border almost straight, entire, 2.9 times longer than wide, slightly longer than endopod, terminating in a small tooth with small mobile spiniform seta medially (Fig. 61D).
About 30 eggs of ca. 0.5 mm in diameter present under abdomen.
Size. Ovigerous female pocl. 1.75 mm.
Colour. The species was accidentally recorded on video but the footage is not very clear. It seems largely translucent with small scattered white chromatophores at the basis of the tail fan, and appendages, with a red longitudinal line running from the antennulae ventrally over the sternum and abdomen, and a white longitudinal line over the carapace dorsally. The cornea of the eyes is whitish as well as the eggs in the ovigerous females.
Remarks. The present specimens fit the original description by Lebour (1949) and the redescription of the holotype specimen by Heard & Spotte (1991). The holotype ovigerous female (pocl. 2.0 mm) is slightly larger than the largest female (pocl. 1.75 mm) from Bonaire. The holotype has 7 dorsal rostral teeth whereas the two largest females (Fig. 55B, D) from Bonaire have 6 dorsal rostral teeth. The smaller specimens (Fig. 55E–G) from Bonaire have 5 dorsal rostral teeth. A small subdistal vetral tooth on the rostrum described for the holotype is present in two specimens (Fig. 55B, E) from Bonaire; the other specimens (Fig. 55D, F, G) lack a ventral tooth there. The second pereiopods are very unequal as described for the holotype; the proportions of the segments in the material from Bonaire are also similar to those in the holotype. A remarkable feature of the holotype is the rounded form of the tooth on the cutting edge of the major chela movable finger and the absence of a tooth there on the fixed finger (Heard & Spotte 1991: fig. 5d). In the present material a triangular tooth is present on the cutting edges of both fingers (Fig. 58C). Another remarkable feature in the holotype as drawn by Lebour (1949: fig. 4.11) but not mentioned in her description is the dorsolateral longitudinal carina on the dactylus of the major second chela. This feature is also striking in the material from Bonaire (Fig. 58B–D). In the holotype the dactylus of the major chela is curving over and extending well beyond the fixed finger; in the material from Bonaire this is also observed, but not as distinct as in the holotype. The ambulatory pereiopods (Fig. 60) are as described for the holotype; with biunguiculate dactyli and few sets of spines in the distal part of propodal flexor margins; these spines are finely serrate in the present material which has not been noted for the holotype. The armament of the telson is as in the holotype, including the median acute process on the posterior margin (Fig. 56C).
The present specimens could well be conspecific with P. iridescens. Periclimenes iridescens has been recorded in the western North Atlantic several times: off Venezuela (Holthuis, 1951b), Tobago (Chace 1972; Abele & Kim, 1986), Curaçao and Bonaire (Criales 1980), Colombia (Criales 1984); Islas del Rosario, Columbia (Corredor et al. 1979); Florida Gulf coast (Hopkins et al. 1977; Herbst et al. 1979; Williams 1984), Cape Hatteras, North Carolina (Herbst et al. 1979; Williams 1984), Los Roques (Grajal & Laughlin 1984; Rodríguez 1986), Martinique (Carré 2005; Poupin 2018), and Cubague (Hernández-Ávila et al. 2007). However, most of these records are doubtfull as several closely related and very similar species have been described in the species complex since: P. patae Heard & Spotte, 1991; P. antipathophilus Spotte, Heard & Bubucis, 1994; P. mclellandi Heard & Spotte, 1997; P. colesi De Grave & Anker, 2009; and P. sandyi De Grave, 2009. Another species initially recognized in the P. iridescens species complex as P. siankaanensis Martínez-Mayén & Román-Contreras, 2006 was subsequently transferred to the genus Phycomenes Bruce, 2008 (Bruce 2010).
Ecology. The present material was collected from considerable depth (42 m) as was the holotype specimen (80–100 ftms (= 146–183 m)). As the holotype of P. iridescens was collected by tow-net, a possible host was not recorded. The present material was collected from a tuft of algae overgrowing Millepora sp. overgrowing a S. luetkeni wire coral with the crinoid N. grandis on which the shrimp was also recorded.
Distribution. The distribution of the species remains unclear due to the confusion with other species within the P. iridescens species complex (see below). Criales (1980) mentioned P. iridescens from both Curaçao and Bonaire.
description: Published as part of Fransen, Charles H. J. M., 2023, The marine palaemonid shrimps (Crustacea, Deapoda, Caridea) of the Dutch Caribbean, pp. 1-127 in Zootaxa 5387 (1) on pages 83-91, DOI: 10.11646/zootaxa.5387.1.1, http://zenodo.org/record/10698994