Bioacoustics of Palinustus mossambicus

Puerulus stage The morphological description is based on the puerulus from Zanzibar . Carapace ( Fig. 1 A, B, C). Rostrum absent; anterior margin of carapace with a pair of spines plus a minute solitary spine, without medium spine; supraorbital horns widely separate and truncate, with a strong spine on the outer margin, anterior margin smooth and unarmed; inner margin of supraorbital horns without spines; anterior margin of epistome with a small spine on anterolateral corners, anterior margin without spines or tubercles; postorbital, antennal and branchiostegal spines present, postorbital more short than antennal and branchiostegal; cervical groove well defined; well-developed stridulating organs present; post-cervical spines as showed. Sternum ( Fig. 2 B). Sternites 1 and 2 completely fused; lateral margins of sternites 4–5 and sternites 6–8 with one and two processes respectively; with nine minute medial tubercles arranged 2,2,2,2,1. Antennule ( Fig. 1 A). Well developed; proximal segment of peduncle shorter than antennal peduncle; outer flagellum 25-segmented, more robust than the inner (missing distal part). AP1 = 7.0 mm, AP2 = 2.0 mm, AP3 = 4.3 mm . Antenna ( Fig. 1 A, 2A). Peduncular spines as illustrated; plectrum present on basal segment of the peduncle; flagellum very spinose. Mandible. Incisor and molar processes undifferentiated, uncalcified and without teeth; palp unsegmented and without setae. Maxillule ( Fig. 3 A). Poorly developed and sparsely setosed; coxal endite with seven terminal minute spines; basial endite with about 8 terminal minute spines and two minute setae; endopod unsegmented, with three terminal simple setae. Maxilla ( Fig. 3 B). Three endites present, the distal endite elongated, with four spines and eleven setae, longer than the others, proximal endite with six setae and medial with four setae; endopod unsegmented with two apical simple setae and nine plumose setae on outer margin; scaphognathite (exopod) large and well developed, with about 150 plumose marginal setae. First maxilliped ( Fig. 3 C). Endites absent, the unsegmented endopod rudimentary and sparsely setosed; exopod large and flagellated, with 22 proximal plumose setae on outer margin, flagellum with about 20 segments, more differentiated distally, each segment with 2 setae (minute proximally; long and plumose distally). Second maxilliped ( Fig. 3 D). Gill present and well developed; endopod 4-segmented, with 5,0,6,6 setae; exopod long and flagellated, approximately twice the endopod length; flagellum with about 23 segments more differentiated distally; each segment with two setae (minute proximally; long and plumose distally). Third maxilliped ( Fig. 4 A). Endopod 5-segmented; ischium sparsely setosed with 6 acute spines on inner margin (crista dentata); merus with a few small setae, and an acute distal outer spine; carpus, propodus and dactylus densely setose; exopod large with a flagellum reaching beyond base of carpus; flagellum with about 23 annulations more differentiated distally, each annulation with two setae (minute proximally; long and plumose distally). Pereiopods ( Fig. 1 A). 1–5 with segmented and well developed endopod; heavily spinulose; merus and carpus of pereiopods 1–5 with a two acute distal marginal spine; pereiopods 1 and 5 are the shortest (16.7 and 16.0 mm, respectively) and pereiopods 2 and 3 are the longest (about 18 mm ); pereiopod 5 is thinner and not as spinulate or setosed as the other pereiopods. Abdomen ( Fig. 1 A, 2A). Transverse groove present in somites 1–4, and slightly marked in somites 5 and 6; tergite of somite 6 with three pairs of spines, posterior margin with two pairs of spines ( Fig. 1 D); pleural plates of the somites 2–6 terminating in two strong spines directed ventrally. Pleopods ( Fig. 4 ). Somites 2–5 each with one pair of well developed biramous pleopods; protopod with about 13 plumose setae and a few spines on inner margin; endopod unsegmented with about 58 long marginal plumose natatory setae and appendix interna with 7 distal setae on outer margin and about 12 terminal coupling hooks on inner margin; exopod unsegmented with about 60 long marginal plumose natatory setae. Uropods ( Fig. 1 A). Biramous; with 3–4 spines on inner margin of the calcified part; the posterior margin of the uncalcified part setose. Telson ( Fig. 1 A). With two pairs of dorsal spines; the lateral margin of the calcified part with two pairs of spines (one medial and one distal) and the inner margin bears three pairs of spines; the posterior margin of the uncalcified part setose. Table 1. Comparative morphology of the second and third maxillipeds of several palinurid species Adult Adult Puerulus Puerulus Puerulus Puerulus Source exopod exopod CL (mm) exopod exopod 3rdmxpd 2nd mxpd 3rd mxpd 2nd mxpd 3rd mxpd crista flagellated flagellated flagellated flagellated dentata