Periclimenes crinoidalis Chace, 1969

Vera-Caripe, Jonathan Alejandro, Gómez, Carlos Federico Lira, Tucker, Gabriela Carias & Agudo-Padrón, Aisur Ignacio, 2019, New records of the shrimp Periclimenes crinoidalis Chace, 1969 (Decapoda: Palaemonidae) and its crinoid host Nemaster grandis A. H. Clark, 1909 (Echinodermata: Crinoidea) in the Caribbean Sea, Nauplius (e 2019005) 27, pp. 1-9 : 3-6

Periclimenes crinoidalis Chace, 1969

Periclimenes crinoidalis Chace, 1969: 251 , Figs. 1 , 2 — Chace, 1972: 34.— Críales, 1984: 309.

Description: Rostrum slightly upturned in males and largest females, overreaching half of second antennular segment in males and extending to the distal margin of the third segment in females. Dorsal margin armed with 6–8 spines in males, and 8–10 spines in females, the first proximal spine placed almost at level of the orbital margin; ventral margin of the rostrum armed distally with a small spine (sometimes absent) in males and with 3 spines in the females. Antennal spine strong, slightly smaller than the ventral angle of the orbit; slimmer and shorter than hepatic spine.

Cornea pigmented, fill almost half of the ocular peduncle.

Antennular peduncle with stylocerite sharp and slender, reaching nearly to mid length of basal segment; first segment armed with 2-3 subequal spines in the distolateral margin.

Antennal scale overreaching distal margin of the third antennular segment, three or slightly more than three times longer than wider. Basal segment of the scale with a strong spine near the base.

Third maxilliped with exopod reaching the distal margin of the first segment. The rest of the mandibular appendices were not examined.

First pair of pereiopods reaching the distal margin of the antennal scale; merus about twice as long as the ischium; carpus slightly longer than chela and slightly shorter than merus; fingers of the chela longer than palm, unarmed. Second pereiopods subequal in males, overreaching antennal scale by distal third to entire length of fingers; fingers slender, unarmed, about three-fourths as long as chela and shorter than merus; ischium slightly shorter than merus. Second pairs of pereiopods unequal in shape and size in females, the left bigger than the right. Major cheliped reaching antennal scale with the carpus; fingers of the chela more than half the length of the palm, incurved in horizontal plane, apexes acute and hook-shaped, crossed distally; cutting margins of both fingers with a pair of the small proximal teeth. Minor cheliped exceeds the antennal scale with proximal end of the fingers; fingers longer than palm. Third pair of pereiopods overreaching antennal scale, dactyls simples, with a small projection in the mid length of the flexor margin. Fourth pair reaching with the dactylus 2/3 of antennal scale. Fifth pair of pereiopods almost reaching the distal end of the antennal scale, dactyls wider than in the third and fourth pair of pereiopods.

Abdomen with all pleura rounded.Third abdominal somite produced posteriorly in a dorsal hump shape projection over base of fourth somite. Fifth somite more than half the length of the sixth.

First pair of pleopods of males with margin of endopod entire and not bilobate, second pair with appendix masculina and subequal endopods.

Telson slightly longer than sixth somite, not including terminal spines; dorsal spines very small but distinct, the proximal pair located approximately in the mid length of the segment and the distal pair at ¾ of the length of the telson; terminal spines very different in length and width, the most lateral pair is shorter than the 2 remaining pairs, intermediate pair wider and slightly longer than the mesial pair. Uropods characteristic of the genus.

Material examined. 4 males, 2016-Dec-10 (CL1.19– 1.58 mm), 1 ovigerous female 2016-Dec-10 (CL 2.36 mm with bopirid isopod) and 1 non-ovigerous female, 2016-Aug-29 (CL 2.39 mm). The six specimens were found in association with the crinoid Nemaster grandis sensu lato at 15 m depth.

Type locality. Jan Thiel Beach , Curaçao, Netherlands Antilles .

Geographical distribution. Jan Thiel Beach, Curaçao ( Chace, 1956); Neguange Bay, Santa Marta, Colombia ( Críales, 1984) and Chichiriviche de la Costa, Vargas State, Venezuela (present study).

Remarks. The specimens of P. crinoidalis collected at Chichiriviche de la Costa fit in almost entirely with the description made by Chace (1969). However, the ovigerous female presented 10 spines in the dorsal margin of the rostrum, instead of the9 spines described by Chace (1969). Moreover, different color patterns were observed, which apparently depend not only on the crinoid host but also on the sex of the shrimps ( Figs. 3 , 4 ).

Ecological aspects. The six specimens of P. crinoidalis were found associated with crinoids of the species N. grandis (sensu lato) ( Fig. 1 ). This supports the observations from different authors who argue that this association appears to be species-specific ( Chace, 1969; Críales, 1984; De Grave, 2014); however, if nominate Nemaster cf. grandis is actually another species, then this hypothesis should be rejected, but the color patters of the shrimps are remarkably different from each other and each color morph correspond to its specific (also different colored) host. During the course of this investigation we believed that we had several species of Periclimenes , but the morphology of the shrimps did not support this idea. Further studies using molecular analysis would be necessary to clarify if they are the same species or a species complex instead.

According to the observations of one of the authors ( GC), while this crinoid is relatively abundant in Chichiriviche de la Costa in depths ranging from 5–18 m, the number of shrimps per host seems to be low (2–6 shrimp per crinoid, sometimes no shrimps were observed); however, this observation could be a underestimation of the real abundance due to cryptic coloration of P. crinoidalis ( Fig. 2 ), as it has previously been suggested by Chace (1969).

Although the type of association between the echinoderm and the shrimp is not analyzed in the present study. Bauer (2004) considers that the invertebrates that host shrimps not only provide refuge, but are also source of food; this author explains that in the case of the echinoderms, symbionts feed on epithelial cells when they detach to be replaced by new ones. Additionally, Bauer (2004) suggests that in the case of the crinoids, the shrimp symbionts can be cleptocommensals, feeding on the material filtrate of the water and concentrate on the ambulacral grooves with lead to the host´s mouth.

Records of decapods associated with echinoderms in Venezuela are scarce ( Tab. 1 ) and the available information is contained in unpublished works ( Lira, 2004; Castro-Guillén et al., 2005; Núñez, 2013; Gómez-Maduro et al., 2016) and publications of faunal inventories ( Chace, 1956; Haig, 1956; Gore, 1974; Rodríguez, 1980; Blanco-Rambla and Liñero, 1994), with very little or no description about the kind of association.

Up to date, 21 species of decapods associated 9 species of echinoderms (two indeterminated) have been reported for Venezuela ( Tab. 1 ). Some of those associations could be accidental, because the crustaceans involved can be found in a great variety of other substrates [ Alpheus formosus Gibbes, 1850 ; Petrolisthes politus ( Gray, 1831) ; Petrolisthes armatus ( Gibbes, 1850) ; Madarateuchus vanderorsti ( Schmitt, 1924) ; Calcinus tibicen (Herbst, 1791) ; Clibanarius tricolor ( Gibbes, 1850) ; Damithrax hispidus (Herbst, 1790) ; Acanthonyx petiverii H. Milne Edwards, 1834 ; Mithraculus forceps A. Milne-Edwards, 1875 ], while others seems to be obligatory [ Gnathophylloides mineri Schmitt, 1933 , Teleophrys pococki Rathbun , 1924; Dissodactylus spp. ], or even more species-specific [ Periclimenes crinoidalis Chace, 1969 ; Minyocerus angustus ( Dana, 1852) ; Clypeasterophilus stebbingi ( Rathbun, 1918) ].

Figures

Figure 1. Crinoid Nemaster grandis, in Chichiriviche de la Costa, Vargas State.

Figure 2. Mimicryof the shrimp Periclimenes crinoidalis associated with the crinoid Nemaster cf.grandis, in Chichiriviche de la Costa, Vargas State, Venezuela.

Figure 3. Ovigerous female of Periclimenes crinoidalis (CL 2.36 mm), associated with the crinoid Nemaster grandis, in Chichiriviche de la Costa, Vargas State, Venezuela.

Figure 4. Male of Periclimenes crinoidalis (CL 1.58 mm), associated with the crinoid Nemaster cf. grandis, in Chichiriviche de la Costa, Vargas State, Venezuela.