Percnon

Abstract: The megalopae and first crab instars are described for three of the four Indo-west Pacific species of the grapsid crab Percnon—P. abbreviatum, P. guinotae and P. planissimum. Keys are provided to these three species and for the Atlantic/East Pacific P. gibbesi. The validity of separating P. planissimum and P. gibbesi is discussed, as are the implications of the unusually large megalopa in Percnon.

Abstract: The grapsoid and gall crab fauna of Easter Island is reviewed, based on historical records and material collected by the Science Museum of Long Island Easter Island Expedition of 1998–1999. Previously, nine grapsoids identified to the species level, but no gall crabs, were recorded from the island. The present work reports on eight species of grapsoids: Pachygrapsus laevimanus Stimpson, 1858 (previously recorded from the island as Pachygrapsus transversus [Gibbes, 1850]); Pachygrapsus plicatus (H. Milne Edwards, 1837) (new record); Leptograpsus variegatus (Fabricius, 1793); Cyclograpsus longipes Stimpson, 1858; Ptychognathus easteranus Rathbun, 1907; Percnon pascuensis Retamal, 2002 (redescribed and figured); Guinusia dentipes (De Haan, 1835); and Guinusia integripes (Garth, 1973) (new combination). Geograpsus crinipes (Dana, 1851) and Guinusia chabrus (Linnaeus, 1758) have been previously recorded from the island; no material of the former was collected and the latter is considered an erroneous identification of Guinusia dentipes. Dacryomaia japonica (Takeda & Tamura, 1981) is the first identified gall crab from the island. Color notes for six species and illustrations for several important morphological characters of Percnon pascuensis are provided.

Abstract: During 1999 CIMAR V expedition covering the waters and bottoms surrounding Pascua and Salas y Gomez islands many organisms inter and subtidal were collected, among them Percnon, new genus for chilean waters and P. pascuensis n. sp., here described.

Abstract: Percnon sinense sp.nov.Carapace thin,slightly longer than broad;covered with short bristles but leaving some symmetrical,raised linear patches bare.There are four fine granules arranged squarely at the basal portion of the epibranchial region;near the middle of the postero-lateral border there are three same granules arranged obliquely in a straight line.Front narrow,with four acute spines.Anterior margin of epistome armed with three spines.Antero-lateral borders of carapace cut into four sharp teeth (including the external orbital tooth).Chelipeds of male slightly unequal in size.Arms slender,with a row of 4-5 short spines on the dorsal surface,the distal end of inner border with a short spine,the outer border with 2-3 small spines,the inner lateral surface with short hairs.Dorsal surface of the carpus with 7-9 short spines and with hairs.Palm slightly longer than broad,the dorsal surface of the basal portion armed with 6-7 small spines coated with short hairs.Fingers short,hollowed out.Chelipeds of female very small.Dorsal surface of the coxa of the 4th walking legs armed with three small spines.Abdomen of both sexes with the 3rd to 5th segments fused.The first abdominal appendage of male stout,with long hook at the extremity.This new species closely resembles Percnon planissinmm (Herbst,1804),but differs from the latter in the following: