Metopograpsus messor, (FORSKAL, 1775)

Flores, Augusto A. V., Paula, José & Dray, Tiago, 2003, First zoeal stages of grapsoid crabs (Crustacea: Brachyura) from the East African coast, Zoological Journal of the Linnean Society 137 (3), pp. 355-383 : 365-368

METOPOGRAPSUS MESSOR (FORSKÅL, 1775) (FIGS 7,8)

Metopograpsus messor ; Chhapgar, 1956 [publication not seen]; Rajabai (1961): 156 –158, Text-fig. I; Hashmi, 1971: 105–107, figs 1,2; Al-Khayat & Jones, 1996: 803,806, fig. 4.

Dimensions: TT 1.13 mm ± 0.04, CW 0.37 mm ±

0.01, CL 0.53 mm ± 0.04.

Carapace ( Fig. 7a ): with a slight postero-dorsal protuberance; dorsal spine straight; rostral spine relatively long, anteriorly directed; lateral spines absent; a pair of dorsal setae present; eyes sessile.

Antennule ( Fig. 7b ): uniramous, endopod absent; exopod unsegmented bearing 2 terminal aesthetascs and 2 unequal terminal setae.

Antenna ( Figs 7a,c ): much shorter than rostral spine; protopodal process anteriorly covered with numerous spines of similar size; endopod absent; exopod absent.

Maxillule ( Fig. 8f ): epipod seta absent; coxal endite with 6 (3 sparsely plumose, 3 plumodenticulate) setae; basial endite with 5 (1 subterminal, sparsely plumose; 4 stout, terminal plumodenticulate) setae, 1 acute tooth in distal margin; endopod 2-segmented, proximal segment with 1 (simple) seta, distal segment with 5 (1 subterminal, plumodenticulate + 4 distal, plumodenticulate) setae; exopod seta absent.

Maxilla ( Fig. 8g ): coxal endite bilobed bearing 5 (sparsely plumose) + 4 (sparsely plumose) setae, basial endite bilobed with 5 (1 sparsely plumose, 4 plumodenticulate) setae + 4 (plumodenticulate) setae; endopod bilobed with 2 (1 longer plumodenticulate, 1 shorter sparsely plumose) setae + 2 (sparsely plumose) setae; scaphognathite (exopod) margin with 4 plumose setae and 1 long distal stout process.

First maxilliped ( Fig. 8h ): basis with 8 setae (arranged 2 sparsely plumose; 1 sparsely plumose, 1 simple; 1 sparsely plumose, 1 simple; 1 sparsely plumose, 1 simple); endopod 5-segmented with 1 (sparsely plumose), 2 (sparsely plumose), 1 (plumodenticulate), 2 (plumodenticulate), 5 (1 subterminal simple + 4 terminal plumodenticulate) setae; exopod unsegmented with 4 terminal plumose natatory setae.

Second maxilliped ( Fig. 8i ): basis with 4 setae (arranged 1 sparsely plumose, 1 sparsely plumose, 1 sparsely plumose, 1 sparsely plumose); endopod 3- segmented with 0, 1 (denticulate), 5 (1 subterminal denticulate + 1 subterminal simple, 3 terminal sparsely plumose) setae; exopod unsegmented with 4 terminal plumose natatory setae.

Third maxilliped: absent

Pereiopods: absent

Abdomen ( Figs 7a,d ): 5 somites; somite 2 and 3 with 1 pair of dorsolateral processes ventrally; posterolateral processes reduced in somite 1, short and nearly blunt in somites 2 and 3, forming large lateral expansions in somites 4 and 5, much larger in the latter; a pair of median postero-dorsal setae in somites 2–5; maximum abdomen width at somite 5.

Telson ( Figs 7d,e ): small setae distributed in scattered patches, nearly covering the forks; lateral and dorsal medial spines absent; forks small, slightly divergent; posterior margin with 3 pairs of stout setae regularly spinulated as shown in Fig. 7 (e).

Figures

Figure 7. Metopograpsus messor (Forskål). First zoeal stage: (a) lateral view; (b) antennule; (c) antenna; (d) dorsal view of abdomen; (e) detail of telson. Scale bars as in Figure 1.

Figure 8. Metopograpsus messor (Forskål). First zoeal stage: (f) maxillule; (g) maxilla; (h) first maxilliped; (i) second maxilliped. Scale bars as in Figure 2.