Periclimenaeus aff. atlanticus ( Rathbun, 1901 )

Fransen, Charles H. J. M., 2023, The marine palaemonid shrimps (Crustacea, Deapoda, Caridea) of the Dutch Caribbean, Zootaxa 5387 (1), pp. 1-127 : 36-38

Periclimenaeus aff. atlanticus ( Rathbun, 1901)

( Figs. 16–17 )

Material examined. Curaçao: ZMA. CRUS.D.103185: 1 juvenile, P2 minor missing , R =3/0, pocl. 0.6 mm; St. Michiel , 14.v.1976, depth 3 m, in S. vesparium , collected by P. Hoetjes (fcn. S-140576-I) . ZMA. CRUS.D.103220: 2 specimens, pocl. 1.1 mm , R =3/0; pocl. 1.4 mm, R =4/0, material damaged, dried out; near Blauwbaai , 11.ii.1976, depth 20 m, from Agelas dispar Duchassaing & Michelotti, 1864 , collected by P. Hoetjes (fcn. A-110276-I) .

Remarks. The present specimens are very small (pocl. 0.6 mm) even smaller than the two female type specimens (total length 5.0 and 5.5 mm) described by Rathbun (1901) and redescribed by Holthuis (1951b). Rostra of present specimens with three or four dorsal teeth of which distalmost small, whereas type-specimens of P. atlanticus with four equally developed teeth dorsally; rostrum distally slightly upturned, not overreaching cornea nor basal segment of antennular peduncle ( Fig. 16A, B ) whereas just overreaching basal segment of antennular peduncle in type specimens of P. atlanticus . Carapace without supraorbital tooth or tubercle; inferior orbital angle slightly developed ( Fig. 16B ). Scaphocerite relatively long, distincly overreaching antennular peduncle ( Fig. 16B ), whereas not overreaching penultimate segment of antennular peduncle in P. atlanticus ; distolateral tooth of scaphocerite moderately developed, reaching distal margin of lamina, whereas more strongly developed in types of P. atlanticus . Carpocerite short ( Fig. 16B ), reaching midlength of scaphocerite whereas overreaching distal lamina of scaphocerite in types of P. atlanticus . Antennal tooth robust. Infraorbital margin angular, not produced. Pterygostomial margin rounded, not produced ( Fig. 16A ). Second pereiopods equal in size, unequal in shape. Major chela with few acute tubercles along median margin of ischium and merus; carpus cup shaped; palm swollen; fixed finger with distinct fossa, medially flanked by triangular knob, distal cutting edge entire, tip strongly hooked; movable finger with well developed plunger, distal cutting edge denticulate, tip strongly hooked ( Fig. 17A ). Both minor cheliped fingers with crenulated tooth in proximal part of cutting edge; distal part of cutting edge finely denticulate, more extensive in dactylus than in fixed finger ( Fig. 17B ). According to Holthuis (1951b) these shallow denticles are not present on the cutting edge of the fixed finger in the type material of P. atlanticus . Third pereiopods with distoventral part of propodus ( Fig. 17C, D ) with one subdistal ventral and one distoventral spine, both minutely tuberculate on flexor margin; dactylus slender with flexor margin of corpus with small obliquely forward directed accessary tooth and acute, slightly forward directed, posterior tooth. This posterior tooth is mentioned by Rathbun (1901) but not shown in the drawing ( Fig. 28c ) whereas it is not mentioned in the description by Holthuis but visible in his plate 24, figure o. Fifth pereiopod ( Fig. 17E, F ) similar to third, propodus with only few distolateral serrulate setae. First abdominal somite without anterior median dorsal lobe. Sixth abdominal segment with posterolateral margin with small tooth ( Fig. 16C ). Distolateral margin of exopod of uropod without tooth, with small mobile spine just medially of distolateral angle ( Fig. 16C ). Dorsal pairs of spines on telson of moderate length; anteriormost pair at 0.25 of telson length, posteriormost pair at 0.55 of telson length ( Fig. 16C ). This differs from P. atlanticus where the anterior pair is placed at about 0.4 and and the posterior pair at 0.75 of the telson length. Lateral pair of terminal spines placed almost in line with other terminal spines, not disctinctly subdistal or submarginal ( Fig. 16D ).

The specimens at hand are in a bad condition and very small. Although there are similarities with P. atlanticus , there are also some clear differences. It is therefor not possible to identify them here with full certainty.

Ecology. Previous records of the species did not mention a potential host ( Holthuis, 1951b). The present specimens were found in two poriferan hosts: S. vesparium , and A. dispar .

Distribution. Records of P. atlanticus are scarce: St. Thomas, Virgin Islands ( Rathbun 1901); Isla de Cozumel and Bahía de la Ascención, Quintana Roo, Mexico ( Chace 1972); Indian River, East Florida ( Reed et al. 1982); in depths between 6 and 42 m. This is the first record of the species from Curaçao, if conspecific.

Figures

FIGURE 16. Periclimenaeus aff. atlanticus Holthuis, 1951b, ZMA.D.103185, juvenile, pocl. 0.6 mm.A, carapace and anterior appendages, lateral; B, anterior appendages, dorsal; C, tailfan; D, distal margin telson. Scale bars: A=1.0 mm; B=0.5 mm; C=0.25 mm; D=0.125 mm.

FIGURE 17. Periclimenaeus aff. atlanticus Holthuis, 1951b. A, ZMA.CRUS.D.103220, pocl. 1.4 mm; B–F, ZMA.D.103185, juvenile, pocl. 0.6 mm. A, right major second pereiopod, mesial view; B, left minor second pereiopod, chela, mesial view; C, right third pereiopod; D, idem, dactylus and distal part propodus; E, right fifth pereiopod; F, idem, dactylus and distal part propodus. Scale bars: A=1.0 mm; B=0.25 mm; C, E=0.5 mm; D, F=0.125 mm.

FIGURE 28. Periclimenaeus cloacola spec. nov., RMNH.CRUS.D.57883, ovigerous female, pocl. 2.9 mm. A, right fifth pereiopod, mesial view; B, idem, dactylus and distal part propodus; C, left first pleopod. Scale: A=1.25 mm; B=0.125 mm; C=0.5 mm.