Periclimenaeus mcmichaeli Ramos-Tafur & Lemaitre 2017, sp. nov.
Creators: name: Ramos-Tafur, Gabriel E.
name: Lemaitre, Rafael
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Palaemonidae
Periclimenaeus
Periclimenaeus mcmichaeli

description: Periclimenaeus mcmichaeli sp. nov.
(Figs. 1–5)
Holotype. Male, CL 8.9 mm, POCL 5.8 mm, TL 19.5 mm, R/ V Tommy Munro, station SMP 1 71402077, 24°45’44’’N, 83°37’38’’W, about 75 km W of Dry Tortugas National Park, Florida, Gulf of Mexico, 15 June 2014, 66– 67 m, bottom trawl, USMN (1441819).
Description of male holotype. Carapace smooth (Fig. 1), glabrous; supraorbital, epigastric and hepatic areas unarmed, lacking teeth or spines; antennal spine well developed, terminating acutely, reaching middle part of basicerite. Branchiostegal area broadly rounded, slightly projected anteriorly; cardiac and hepatic regions unarmed, margins smooth, rounded.
Rostrum long, straight, slightly inclined (Figs. 2 A, C), compressed laterally, overreaching distal end of third antennular segment by more than 1.2 length of third antennular segment; dorsal margin armed with 11 acute, evenly distributed teeth from tip to orbital margin, and having short setae between teeth; ventral margin slightly convex, naked, armed with 2 small subdistal teeth positioned at about level of second dorsal tooth of rostrum (Fig. 2 C).
Eyes well developed (Figs. 2 B, C), distal margin of cornea reaching to about 0.6 length of first antennular segment, or to level of fourth and fifth dorsal teeth of rostrum. Peduncle inflated medially, wider than cornea.
First antennular segment about 2.1 times as long as wide, lateral margins sinuous, distolateral margin projected as acute tooth with tip reaching distal third of second antennular segment, ventromesial margin with tiny acute tooth; second segment unarmed, about 0.8 as long as third antennular segment. All segments with short setae (Fig. 2 C).
Right stylocerite ending in acute tooth, with tip not reaching distal margin of cornea; left stylocerite similar (tip broken during capture). Scaphocerite well developed, about 2.2 times as long as wide, slightly overreaching distal margin of third antennular segment; lateral margin slightly concave, ending in acute distolateral tooth not exceeding distal margin of squamous portion. Basicerite subquadrangular, unarmed. Carpocerite distal end overreaching slightly distal margin of second antennular segment.
Mandible (Fig. 3 A) without palp. Incisor process elongate, tapering distally and ending in 2 small acute teeth; molar process robust, broadly truncate distally, with 3 rounded teeth plus 1 small acute tooth on inferior angle. Left and right mandibles similar.
Maxillule (Fig. 3 B) with palp well developed, distally bilobed, upper lobe rounded, short; inferior lobe subrectangular, slightly curving inwardly, with 2 distal, recurved spinules, lower spinule with globose base (Fig. 3 C); endite bilobed, with lower lacinia foot-shaped, expanded distally and with 12 long, slender marginal pappose setae; upper lacinia broad, upper margin convex, mesial margin furnished with numerous setae, some pappose, others stout, cuspidate and having rugose protuberances or irregular scales distomedially (Fig. 3 D).
Maxilla (Fig. 3 E) with scaphognathite ovoid, well developed, anterior lobe more slender than posterior lobe, margins covered by dense plumose setae. Palp simple, without setae, reaching to mid-level of scaphognathite anterior lobe. Distal endite entire, with 19 distomarginal plumose setae.
First maxilliped (Fig. 3 F) with elongated palp not reaching distal margin of caridean lobe and with 2 simple subdistal and 1 simple distal seta (Fig. 3 G). Exopodal flagellum long, exceeding caridean lobe by more than half its length; with several marginal short simple setae on distal half, and 5 long apical plumose setae. Caridean lobe well developed, with marginal plumose setae. Epipod bilobed, without setae, upper lobe rounded, lower lobe subrectangular. Endite ovoid, without clear division between distal and proximal endites, and short plumose setae present on median and distal margins.
Second maxilliped (Fig. 3 H) with dactylar segment elongated, ovoid, furnished with abundant cuspidate setae; propodal segment slightly produced on inferior and superior margins, with several pappose setae on superior margin and on articulation with dactylar segment; carpus cup shape, without setae; merus and ischio-basis both without setae; exopod elongated, with 4 long subdistal plumose setae and 4 long distal plumose setae. Epipod rounded. Medial margin of coxa projected distally as rounded protuberance, furnished with 3 submarginal simple setae.
Third maxilliped (Fig. 3 I) with tip overreaching distal end of carpocerite by 0.5 length of ultimate segment. Coxa distoventrally rounded, slightly projected, unarmed, without setae or spines; lateral plate subquadrangular, with rounded corners; without arthrobranch. Basis with ventral margin slightly projected, with 12 plumose setae. Ischio-merus fused to basis, about 4.0 times as long as wide, with ventral and dorsal margins sinuous, ventral margin covered with abundant marginal plumose setae. Penultimate segment about 4.3 times as long as wide, about 0.8 as long as antepenultimate segment, ventral margins covered with abundant plumose setae, and small bunch of short plumose setae on distoventral and distodorsal margins; ultimate segment about 0.6 times length of penultimate segment, slightly tapering distally, distal end rounded, covered with abundant plumose setae; dorsal margin with scarce tiny setae. Exopod elongated, tip reaching near proximal third of antepenultimate segment, with 4 long distal plumose setae and single plumose seta on ventral margin close to the tip.
First pair of pereopods (Fig. 5 C) similar left from right in shape and length, overreaching tip of rostrum by entire length of carpus. Basis with 5 setae on proximoventral margin. Ischium about 0.3 length of merus, ventral margin convex, slightly swollen, with scarce small simple setae, distal end of dorsal margin with single short plumose seta. Carpus and merus subequal in length; distal end of dorsal margin of merus with single seta; ventrodistal margin of propodus with several plumose setae. Chela about half length of carpus; fingers about 0.4 as long as chela, tips of fingers bifid (Fig. 5 D), cutting edges each covered with short plumose setae and slender straight spinules; external surface of palm and fingers with abundant tufts of plumose setae.
Second pair of pereopods dissimilar in size and shape (Figs. 1 A, B). Right second pereopod or major cheliped massive, distinctly longer than body when tail is bent. Ischium about 0.45 as long as merus (Figs. 4 C, D); with strong excavation proximally. Merus about 1.9 times as long as broad, dorsal margin concave, inferior margins sinuous, smooth, with 2 minute tubercles (visible only under high magnification), distal margins not projected. Carpus subtriangular in external view, subquadrangular in mesial view; inferior and superior margins projected, each ending in rounded knob. Chela about 2.5 times as long as wide, fingers about 0.3 as long as chela; palm ovoid in cross section; external surface of palm (Fig. 4 A) with numerous dense, small tubercles and pits on distal half; fixed finger with tip ending in rounded tooth, cutting edge deeply excavated, forming fossa to receive dactylus plunger and partially covered by rounded marginal elevation with scarce setae; with conspicuous rounded projection on upper part of dactylar articulation followed by narrow U-shaped notch. Dactylus compressed, dorsal margin rounded, ending in triangular acute tip; cutting edge armed with subrectangular plunger having ventral margin slightly concave. Mesial surface of palm (Fig. 4 B) almost totally covered with dense, small tubercles arranged in proximal half forming as irregular honeycomb pattern; proximodorsal margin with semiovoid smooth unarmed area extending to margin of carpus. Pollex with well-defined fossa, cutting edge between fossa and tip of finger laminar (Fig. 2 E). Dactylar articulation flanked with acute triangular tooth very close to fossa and with several small setae, followed dorsally by 2 conspicuous rounded protuberances separated by narrow notch. In ventral and dorsal view (Figs. 4 E, F) distal half of chela abruptly changing to strong concavity and forming internal curvature of fingers.
Left second pereopod (Figs. 4 G–J) or minor cheliped overreaching tip of rostrum by almost entire length of chela. Ischium and merus subequal in size, dorsal margins convex; ventral margin of ischium with scarce small setae, ventral margin of merus smooth, without setae or protuberances; distal margins not projected. Carpus cup shape in external view; in mesial view with swollen irregular protuberances to accommodate articulation of chela in oblique position. Chela ovoid in lateral view; palm subrectangular in cross section, nearly 2.0 times as long as wide; fingers about 0.25 as long as chela. Palm external face with pits and small tubercles on dorsodistal half and inferior margin between fixed finger and middle section, with scarce few setae; ventroproximal half of palm with longitudinal elongated groove. Fixed finger with tip broadly truncated, cutting edge with groove or canal to accommodate armature of dactylus when fingers closed, with several long marginal setae; dactylar articulation flanked by small subtriangular and rounded knob separated by wide subquadrangular notch. Dactylus compressed, laminar, strongly convex dorsally, ending in acute tip, cutting edge with 3 well developed, subequal, evenly separated subtriangular teeth (Fig. 2 D), with cluster of small setae between second and third teeth. Mesial surface of palm covered almost entirely with dense small tubercles and pits; fixed finger with proximal part elevated as subtriangular knob, dorsally with several long setae, and distally with series of small crenulations (Fig. 2 D); dactylar articulation flanked by elevated rounded knob with scarce long setae, and deep subrectangular notch with small rounded knob on bottom.
Third pereopod (Fig. 5 E) overreaching tip of rostrum by entire length of propodus. Basis unarmed. Ischium without teeth or spines, about twice as long as wide. Merus slightly swollen dorsally, about 4.0 times as long as broad, unarmed, with shallow depression on ventrodistal margin. Carpus unarmed, about 4.1 times as long as broad, dorsal margin slightly projected distally. Propodus about 5.0 times as long as broad, armed with row of 5 or 6 spines on ventral margin and pair of spines flanking dactylar articulation. Dactylus tip (Fig. 5 F) broken off.
Fourth and fifth legs similar to third leg except slenderer, fourth longer than fifth. Propodus of fifth leg with tiny spines on ventral margin, and small tuff of distal setae. Dactylar tips of fourth to fifth pereopods or walking legs with tips broken off.
Abdomen (Fig. 2 A) smooth, glabrous, slightly compressed laterally. First pleopod with endopod less than half size of exopod. Second pleopod with short appendix masculina, tip with four elongate plumose setae, appendix interna twice as long as appendix masculina. Sternites with transverse low keel; without spines, protuberances or processes. First abdominal somite with well-developed anterior median lobe on tergite (Figs. 2 A, 5A); ventral margin of pleura forming obtuse angle submedially. Second somite with pleura broadly rounded. Third and fourth segments each with ventral margin of pleura projecting anteroventrally as prominent acute spine (Fig. 5 B), posteroventral margin of pleura rounded. Fifth somite about 1.5 times as long as sixth somite; ventral margin of pleura broadly rounded. Sixth somite with ventral and posterolateral margins of pleura rounded.
Telson (Fig. 5 G) 2.1 times as long as wide, subtriangular, tapering slightly distally, lateral margins nearly straight; dorsal surface with 2 pairs of spines on anterior third. Distal margin (Fig. 5 H) subtriangular, ending in small rounded median tip; armed with 3 pairs of spines, lateral pair the shortest, each spine situated on outermost corner and not reaching level of median tip; intermediate pair of spines strong, longest, more than 3 times length of external pair, and about 1.25 as long as submedian pair. Lateral and submedian spines on right side lost during examination. Uropod with exopod slightly shorter than endopod; left exopod with posterolateral margin ending in acute spine flanked by a pair of movable spines; right uropodal exopod with spines missing; diaeresis slightly curved.
Habitat. Probably lives associated with species of Porifera. The holotype was collected with a fishing trawl together with numerous unidentified sponge specimens or pieces. The many sponge fragments attached to the body of the holotype suggest that the single specimen of Periclimenaeus mcmichaeli sp. nov. may live in association with one or more species of the sponges obtained during the trawling but became detached during collecting.
Etymology. This new species is named in homage to Robert “Bob” McMichael Jr., creator of Florida Independent Monitoring Program (FIM) of FWRI. For more than 35 years he played an important role as founder and director of FIM program, produced at least 40 scientific publications on fisheries, and helped create several FIM field laboratories along both coasts of Florida.
Color (Fig. 1). Recorded only after recently preserved at arrival at FIM laboratory. Overall milky coloration of body and pereopods, with some dorsal areas of carapace yellow ochre. Lateral surfaces of carapace and abdomen reddish brown.
Remarks. Periclimenaeus mcmichaeli sp. nov. is morphologically most similar to its western Atlantic congener Periclimenaeus wilsoni (Hay, 1917). The two species can be separated by the following eight character differences: 1) in this new species the ventral margin of the rostrum is armed with two small subdistal teeth (Figs. 2 A, C), whereas in P. wilsoni the rostrum is unarmed ventrally (Figs. 6 A, 7A, F); 2) the tip of rostrum reaches beyond the distal margin of the third antennular segment, whereas in P. wilsoni the rostrum does not reach the distal margin of the antennular segment; 3) the distal margin of the cornea reaches the level of the fourth dorsal rostral tooth, whereas in P. wilsoni the distal margin reaches the sixth to eight rostral teeth; 4) carpus of first pair of pereopods not inflated distally and chela is 0.5 as long as carpus (Fig. 5 C), whereas in P. wilsoni the carpus is slightly inflated distally and chela is 0.8 as long as carpus (Fig. 6 B); 5) the ventral margin of meri of second pair of pereopods is smooth, unarmed except for minute tubercles on ventral surface of the major cheliped, whereas in P. wilsoni the ventral margin of carpi of major and minor chelipeds is armed with an irregular row of small tubercles; 6) in the holotype male of the new species, the cutting edge of the dactylus of minor cheliped is armed with three well developed teeth, whereas in males of P. wilsoni the cutting edge is armed with a rectangular tooth (Figs. 6 C, D); 7) telson with two pairs of dorsal spines, both situated on anterior third, whereas in P. wilsoni the first pair is situated near the anterior margin, and the second pair just posterior to midlength of telson; and 8) distal margin of the telson is subtriangular and terminates in a small median knob, whereas in P. wilsoni the distal margin is slightly concave throughout (Holthuis 1951: 262, pl. 31b).
At least in recently preserved specimens, the milky white coloration of P. mcmichaeli sp. nov. is similar to that previously described for P. wilsoni by Hay & Shore (1918: 395, as Coralliocaris wilsoni) and Williams (1986: 83).
Periclimenaeus mcmichaeli sp. nov. can be separated from other western Atlantic congeners by the armature of the ventral margin of the rostrum. In P. mcmichaeli sp. nov. the ventral margin is armed with two subdistal teeth, whereas in other congeners the ventral margin is unarmed. In one congener, P. caraibicus Holthuis 1951, there is a single subterminal ventral tooth (Holthuis 1951: 269, pl. 34a) that should not be confused as being subdistal in position. Furthermore, P. caraibicus has one supraorbital tooth or protuberance on the carapace, whereas P. mcmichaeli sp. nov. does not.
Periclimenaeus mcmichaeli sp. nov. bears some similarity also with two other species, P. rhodope (Nobili 1904) from Djibouti, Gulf of Aden, and P. echinimanus Ďuriš, Horká & Al-Horani (2011a) from the Gulf of Aqaba, Red Sea and Great Barrier Reef, Australia. In these two other species the rostrum is armed with one or two small subterminal ventral teeth (vs. with two subdistal teeth in P. mcmichaeli sp. nov.); the tip of the rostrum does not reach the distal margin of third antennular segment (vs. tip overreaching distal end of third antennular segment); the distolateral tooth of the scaphocerite distinctly overreaches the distal end of the lamella (vs. distolateral tooth not overreaching lamella); the pleura of the third and fourth abdominal segments are unarmed, ventrally rounded (vs. with acute anteroventral projections); fingers of minor chela of second pereopods long, about 0.4–0.5 as long as the chela (vs. fingers of minor chela short, about 0.25 of chela length); the cutting edge of the dactylus has a small proximal tooth (vs. cutting edge armed with large rounded teeth); and the position of the two pairs of spines on the dorsal surface of the telson (see Bruce 1974: Figs. 1 C, F; Ďuriš et al. 2011a: Fig. 2 D), with anterior pair near distal margin of sixth abdominal somite, and posterior pair near the midlenght of telson (vs. with both pairs of spines on anterior third of dorsal surface of telson).
The presence of an anterior median lobe on the tergite of the first abdominal somite in Periclimenaeus mcmichaeli sp. nov. places this new species in the P. robustus species-group as defined by Bruce (2005a) and corroborated by Ďuriš et al (2011a).
Species of Periclimenaeus are known to live in the canals of a multitude of different sponges or inside compound ascidians, often sharing the host with species of Synalpheus Bate, 1888. Studies of the interaction between host sponges and shrimps, morphology of mouthparts, and stomach contents, have shown these shrimp to function as semi-parasites feeding on the host tissues although not causing major damage to the sponge host (Ďuriš et al. 2011b; Ashelby et al. 2015). It appears that P. mcmichaeli sp. nov. is also associated with sponges. As previously mentioned, the holotype of this new species was collected along with numerous sponges, although not inside any of them. The sponge fragments found attached to the holotype, however, suggest that the specimen got detached from one of the sponges collected in the trawl, and thus possibly was living in association with a sponge.
description: Published as part of Ramos-Tafur, Gabriel E. & Lemaitre, Rafael, 2017, A new species of shrimp of the genus Periclimenaeus Borradaile, 1915 (Decapoda: Caridea: Palaemonidae) from the southeastern Gulf of Mexico, including a key to the western Atlantic species of the genus, pp. 491-508 in Zootaxa 4303 (4) on pages 493-501, DOI: 10.11646/zootaxa.4303.4.3, http://zenodo.org/record/841492