Gecarcinus ruricola, (LINNAEUS, 1758)

Hartnoll, Richard G. & Clark, Paul F., 2006, A mass recruitment event in the land crab Gecarcinus ruricola (Linnaeus, 1758) (Brachyura: Grapsoidea: Gecarcinidae), and a description of the megalop, Zoological Journal of the Linnean Society 146 (2), pp. 149-164 : 153

publication ID	https://doi.org/ 10.1111/j.1096-3642.2006.00195.x
DOI	https://doi.org/10.5281/zenodo.10545403
persistent identifier	https://treatment.plazi.org/id/03C287EA-FFE8-6563-9D99-FF36FC797D66
treatment provided by	Diego
scientific name	Gecarcinus ruricola
status

Treatment

GECARCINUS RURICOLA ( LINNAEUS, 1758) View in CoL

Carapace ( Fig. 3A View Figure 3 ): rostral small, sharply directed ventrally and slightly inclining posteriorly; carapace sparsely setosed.

Antennule ( Fig. 4A View Figure 4 ): biramous; peduncle 3-segmented with c. 8,8,3 setae, respectively; endopod 1-segmented with 2 subterminal and 2 terminal setae of unequal length; exopod 3-segmented, segment 1 with 5 aesthetascs, segment 2 with 4 aesthetascs and 2 setae, segment 3 with 3 aesthetascs and 2 unequal setae.

Antenna ( Fig. 4B View Figure 4 ): peduncle 3-segmented with 4,3,4 setae, respectively; 7-segmented endopod flagellum with 0,0,4,0,5,3,4 (terminal) setae, respectively. Exopod and protopod lost.

Mandible ( Fig. 4C View Figure 4 ): palp 3-segmented, basial segment without setae; endopod two segmented, distal segment with c. 16 marginal setae.

Maxillule ( Fig. 4D View Figure 4 ): coxal seta present; coxal endite with c. 25 setae; basial endite with c. 34 setal processes; endopod 2-segmented, proximal segment with 2 setae, distal segment with 4 (3 subterminal +1 terminal) setae; exopod seta present.

Maxilla ( Fig. 5A View Figure 5 ): coxal endite bilobed with c. 22 + 10 setae; basial endite bilobed with c. 16 + 20 setae; endopod simple (not bilobed) with 5 basal setae; exopod (scaphognathite) margin with c. 73 setae and 4 lateral setae.

First maxilliped ( Fig. 5B View Figure 5 ): epipod with c. 18 long setae and 1 small basal plus 3 terminal setae; coxal endite with c. 24 setae; basial endite with c. 27 setae; endopod unsegmented with 2 subterminal setae, 1 long-terminal seta sometimes present; exopod 2-segmented, proximal segment with c. 4 distal setae; distal segment with 4 long-terminal plumose feeding setae.

Second maxilliped ( Fig. 6A View Figure 6 ): epipod present with small podobranch gill bud and c. 8 long setae; coxa and basis not differentiated, with 5 setae; endopod 5-segmented, ischium without setation, merus with 1 seta, carpus with 1 seta, propodus with 8 setae, dactylus with 9 marginal setae; exopod 2-segmented, proximal segment with 5 distal setae; distal segment with 5 long-terminal plumose feeding setae.

Third maxilliped ( Fig. 6B View Figure 6 ): epipod with 29 long setae plus podobranch and arthrobranch gill; coxa and basis not differentiated, with c. 29 setae; endopod 5-segmented, ischium with c. 30 setal processes; merus with c. 26 setae; carpus with c. 15 setae; propodus with c. 11 setae; dactylus with 8 setae; exopod 1-segmented, with 1 seta.

Pereiopods ( Fig. 7A–E View Figure 7 ): gills and setation as figured.

Sternal plates ( Fig. 3B View Figure 3 ): plates 1–4 fused, plate 1 without setae, plates 2–4 with c. 46 setae.

Abdomen ( Figs 8A, B View Figure 8 , 9A–E View Figure 9 ): 6 somites present; somite 1 with a row c. 5 pairs of medial setae and a row c. 5 pairs of marginal, plus with 4 lateral setae on each side; somites 2 and 3 each with 1 pair of medial setae and c. 5 pairs of marginal setae plus 3 lateral setae on each side; somite 4 with 2 pairs of medial setae plus c. 5 pairs of marginal setae plus 3 lateral setae on each side; somite 5 with 3 pairs of medial setae and 4 pairs of marginal setae plus 3 lateral setae on each side; somite 6 with 1 pair of marginal setae plus 4 setae on each side; somites 2–5 each with 1 pair of biramous pleopods, endopod unsegmented, with a row of 5 cincinuli on internal margin; exopod unsegmented with c. 31, 32, 30, 27 long marginal plumose natatory setae on pleopods 1–4, respectively; somite 6, uropod uniramous without endopod, proximal segment with 2 setae; exopod segment with c. 17 long marginal plumose natatory setae.

Telson ( Fig. 8A, B View Figure 8 ): telson forks absent; 6 pairs of dorsal and 1 pair of ventral setae plus 3 terminal setae.

Remarks

Six genera have been assigned to Gecarcinidae MacLeay, 1838 ; Cardisoma Latreille, 1828 ; Discoplax A. Milne-Edwards, 1867 ; Epigrapsus Heller, 1862 ; Gecarcinus Leach, 1814 ; Gecarcoidea H. Milne Edwards, 1837 and Johngarthia Türkay, 1970 . Of these genera the larvae are only known for Cardisoma , Gecarcinus and Gecarcoidea (see Table 1). In the Caribbean the megalops are known for two other gecarcinid land crabs, Gecarcinus lateralis described by Willems (1982), and Cardisoma guanhumi by Costlow & Bookhout (1968). These can be compared with and distinguished from the megalop described in the present study (see Table 2). The absence of a distal exopod segment on the third maxilliped in Gecarcinus lateralis and G. ruricola megalops appears to be a distinguishing character for this genus when compared with Cardisoma (see C. guanhumi by Costlow & Bookhout, 1968: fig. 46; C. carnifex by Kannupandi et al., 1980: fig. 56; C. hirtipes by Shokita & Shikatani, 1999: fig. 7i) in which the segment is present with terminal setae.