GLYPTOGRAPSIDAE Schubart, Cuesta & Felder, 2002

Guinot, Danièle, Ng, Ngan Kee & Rodríguez Moreno, Paula A., 2018, Review of grapsoid families for the establishment of a new family for Leptograpsodes Montgomery, 1931, and a new genus of Gecarcinidae H. Milne Edwards, 1837 (Crustacea, Decapoda, Brachyura, Grapsoidea MacLeay, 1838), Zoosystema 40 (26), pp. 547-604 : 574-576

Family GLYPTOGRAPSIDAE Schubart, Cuesta & Felder, 2002

INCLUDED GENERA. — Based on available larval and DNA evidence, Schubart et al. (2002) established a new family for the American and east Atlantic genera Glyptograpsus Smith, 1870 and Platychirograpsus De Man, 1896 , crabs occuring in shallow freshwater streams, from brackish waters at stream mouths to up to several hundred kilometers inland (see also Cuesta & Schubart 1998; Schubart et al. 2006: figs 1-4). Genetic results of van der Meij & Schubart (2014) showed that Glyptograpsidae appeared as sister-group of Heloeciidae H. Milne Edwards, 1852 , a family currently included in Ocypodoidea ( Ng et al. 2008).

DIAGNOSIS

The most conspicuous adult morphological traits are:the striking heterochely shown by the males (unique in Grapsoidea ), the dorsal carapace surface areolated and without striae, the broad mxp3 closing the buccal cavity without gaping and with three longitudinal sulci on the merus (N. K. Ng et al. 2007: fig. 7G), the pleon with somites 3 to 5 inflexible but with sutures, the G1 with a subproximal tuft of setae and elongate, uncinate distal portion, all characters well described by the cited authors.

To these synapomorphies corroborated by molecular studies, some characters must be added: absence of pleonal-locking mechanism, no button, no socket, the pleonal area where the socket is usually located being occupied by the G1’s tip; sterno-pleonal cavity very broad, with conspicuous rim at level of telson; thoracic sternum ( Fig. 8D, E ): suture 2/3 well marked, sternite 1 extending into a narrow process between mxp3; sternite 2 with a membranaceous depression; sternite 8 rather wide but not greatly exposed medially; median line extending on sternite 7; male gonopore with a posteriormost location in relation to sternite 8; penis short, with a sclerotised proximal portion ( Fig. 8F ).

COMPARISON WITH LEPTOGRAPSODIDAE N. FAM .

Glyptograpsidae shares with Leptograpsodidae n. fam . the median line extending on sternite 7, but the sternal emergence of the gonopore far from P5 coxa (N. K. Ng et al. 2007: fig. 4G), the dispositon of sternite 8, the shape of penis are distinctive characters. The glyptograpsid suborbital ridge (N. K. Ng et al. 2007: fig. 5G) does not consist in a stridulatory crest.

Family PERCNIDAE Števčić, 2005

INCLUDED GENERA. — The family is monogeneric, with six species that show an active swimming capacity ( Zenone et al. 2016) by means of a developed setation (rows of postero-dorsal setae) on the long pereiopods that allow them to cling to hard surfaces. Species of Percnidae are, with the Plagusiidae and Varunidae, the only grapsoids able to extensively swim thanks to specialised modifications.

REMARKS

Based on Cuesta & Schubart (1998) and Schubart et al. (2000b, 2006) that questioned the placement of Percnon Gistel, 1848 , Števčić (2005) established the new tribe Percnini , which was adopted as the subfamily Percninae within the Plagusiidae ( Ng et al. 2008) and then separated as a full family on the basis of larval morphology and combined evidence of mtDNA and nDNA by Schubart & Cuesta (2010), a currently adopted taxonomy ( Davie et al. 2015c). Genetic results of van der Meij & Schubart (2014) showed that Percnidae was related to Mictyridae Dana, 1851 , but with very long branches, “an unexpected hypothesis considering the large phylogenetic distance between these two families in the trees of Schubart et al. (2006) and Wetzer et al. (2009).”

DIAGNOSIS

Sternal and male genital characters are here added.Proepistome very narrow. Thoracic sternum flat, remarkable by the absence of anterior sutures, seemingly except for faint suture 1/2, most noticeable medially posterior to small, triangular sternite 1; sternites 2-4 forming a smooth single piece, with straight margins ( Fig. 8G, H ). Episternite 7 long, narrowly extended. Despite a rather deep posterior emargination, sternite 8 very broad, widely exposed medially, although narrower in P. gibbesi . Sternite 8 forming raised protrusion that bears the gynglyme receiving P5 coxo-sternal condyle. When the pleon is closed, a rather large portion of sternite 8 dorsally exposed anteriorly; in addition, a very minute portion visible posteriorly ( Guinot 1979: 209, pl. 23, fig. 2). Episternites 4-6 very narrow. Median line present on sternite 8 and extending on sternite 7. Located in posteriormost location in relation to sternite 8, male gonopore and penis very close to P5 coxa. Gonopore coming into contact with P5 coxo-sternal condyle in P. planissimum (see Guinot 1979: pl. 23, fig. 2; Rodríguez 1992: fig. 11E; Karasawa & Kato 2001: fig. 2.18), P. affine , P. abbreviatum , and P. guinotae ; in contrast, in other species, e.g. P.gibbesi , episternite 7 long, very shortly joining the raised protrusion of sternite 8, therefore gonopore slightly separated. Penis narrow, showing a calcified proximal portion and then a tube ( Fig. 8I ) ( Kienbaum et al. 2018: fig. 1). Presence of a strong press-button with wide base and corneous surface ( Guinot 1979: pl. 23, figs 2, 3; Guinot & Bouchard 1998: 664; Davie et al. 2015c; Emmerson 2016).

The fusion of some pleonal somites is rare in Grapsoidea . In both sexes of Percnidae the pleonal somites 3 to 6 are inflexible although with distinct sutures, in contrast to somites 3-5 fused also with still evident sutures in Plagusiidae and Glyptograpsidae .

The female reproductive system of Percnon gibbesi studied by Kienbaum et al. (2018) exhibits a combination of morphological characters (connection of the oviduct through a separate cuticular duct and presence of a bursa) that has so far been only known in heterotreme crabs. This result supports the conclusion of Schubart & Cuesta (2010) that Percnidae represents a basal split within the Thoracotremata, with an independent phylogenetic origin. Molecular analyses byTsang et al. (2014: figs 1, 2) and Chu et al. (2015: fig. 71-13.2) have also shown that Percnidae emerged basally with cryptochirids and xenograpsids.

A more complete comparison between Percnidae and Leptograpsodidae n. fam . is not necessary in view of their important morphological differences.

Figures

FIG. 8. — Pleon, thoracic sternum and genital region of Grapsoidea: A, D, G, J, M, thoracic sternum (brushed) with pleon; B, E, H, K, N, thoracic sternum (brushed) without pleon; C, F, I, L, O, genital region with gonopore and penis: A-C, Grapsidae: Grapsus grapsus Lamarck, 1801, ♂ 23.8 ×26.9 mm, Antilles, MNHN-IU-2013-10764 (=MNHN-B24641);D-F, Glyptograpsidae:Glyptograpsus jamaicensis (Benedict,1892),♂ 32.8 ×37.4 mm,Jamaica,MNHN-IU-2017-8401 (= MNHN-B127715); G-I, Percnidae: Percnon planissimum (Herbst, 1804), ♂ 29.7× 27.7 mm, Réunion Island,MNHN-IU-2010-19798 (=MNHN-B24534);J-L, Plagusiidae: Plagusia squamosa (Herbst, 1790), ♂ 43.6 ×46.3 mm, Marquesas Islands, MNHN-IU-2011-8947; M-O, Xenograpsidae: Xenograpsus testudinatus N. K. Ng, Huang & Ho, 2000, ♂ 21.8 ×23.8 mm, NE Coast of Taiwan, MNHN-IU-2013-14995 (= MNHN-B30314). Scale bars: 10 mm.