New collections of freshwater crabs from northern Madagascar , with the description of a new species of Foza Reed & Cumberlidge , 2006 ( Brachyura , Potamonautidae ) , and comments on their conservation status

We report here on recent collections of freshwater crabs from Antsiranana Province, northern Madagascar. The specimens belong to three species, one of which is new to science and is described here. This raises the number of species of freshwater crabs found in Madagascar to 17. All are endemic to the island and all belong to the Afrotropical family Potamonautidae Bott, 1970. The new species, Foza manonae sp. nov., is compared to the other species in this genus, and an updated key is provided. It is distinguished from the other three congeners by characters of the male first gonopod, sternum, carapace, and cheliped. The conservation status of the Malagasy freshwater crab fauna is summarized and discussed in light of the new material reported on here belonging to two other species, Madagapotamon humberti Bott, 1965 and Foza ambohitra Cumberlidge & Meyer, 2009.


Introduction
Freshwater crabs are found throughout Madagascar in forested, savanna, and highland habitats, and are particularly species rich in the northern parts of the island where several biodiversity hotspots have been identifi ed (Cumberlidge et al. 2004). These crabs live in lakes, streams, and rivers, as well as in adjacent terrestrial habitats that include rocky crevices and phytotelmata (Cumberlidge et al. , 2005. All freshwater crabs found in Madagascar are included in the Afrotropical family Potamonautidae Bott, 1970(Bott 1960Ng & Takeda 1994;Cumberlidge 1999Cumberlidge et al. , 2007Cumberlidge & Sternberg 2002;Reed & Cumberlidge 2006;Cumberlidge & Meyer 2009;Meyer et al. 2014). The high degree of endemism shown by the Malagasy freshwater crabs (100% at the genus and species levels) is a characteristic that they share with many other freshwater organisms from this longisolated tropical island.
We report here on recent collections of freshwater crabs from Antsiranana Province, northern Madagascar. The specimens belong to two genera: Foza Reed & Cumberlidge, 2006 (that currently includes three species) and , a monotypic genus. Foza was established with the description of F. raimundi Cumberlidge & Reed, 2006, the type species, from Marojejy in northern Madagascar and expanded in 2009 by the inclusion of two other species, F. ambohitra Meyer, 2009 andF. goudoti (H. Milne Edwards, 1853). The fourth species of this genus, Foza manonae sp. nov., described here, is recognized by a combination of morphological characters including those of the mandible, gonopods, carapace, sternum, and cheliped (Table 1).
The new species is described, fi gured, and compared with other species in this genus, and an updated key to the genus is provided. In addition, the conservation status of the Malagasy freshwater crab fauna is discussed for the 14 species known at the time of the last IUCN Red List assessment ). Of these, two species (Boreathelphusa uglowi (Cumberlidge & Sternberg, 2002) and  are currently listed as 'vulnerable to extinction', and fi ve other species are too poorly known to even assess their conservation status (Table 2).

Material and methods
All measurements were made with digital calipers and are given in mm. The terminology is adapted from Cumberlidge (1999) and Cumberlidge & Sternberg (2002). Line drawings were prepared using a Leica MZ 16 stereobinocular microscope. The habitus photographs were taken with a Panasonic Lumix digital camera. Post processing was done in Adobe Photoshop 7.0. Specimens examined are deposited in the Zoologische Staatssammlung München (the Bavarian State Collection of Zoology, ZSM).

Description
Based on holotype (adult ♂, CW 43.7). Carapace outline transversely oval, high (CH/FW 1.75); front narrow (FW/CW 0.28), defl exed; epibranchial tooth small, pointed, extremely advanced in position; anterolateral margin evenly curved outward, lined by small granules; postfrontal crest faint, incomplete postorbital crests, epigastric crests well defi ned, positioned forward on front; deep wide mid-groove between epigastric crests; cardiac urogastric grooves deep, cervical grooves deep posteriorly, faint anteriorly, long, almost reaching postfrontal crest. Anterolateral and posterolateral surfaces of carapace with conspicuous carinae. Suborbital region of carapace sidewall with small granules, subhepatic region with carinae, pterygostomial region heavily granulated with setae in inferior part; vertical sulcus on carapace sidewall curved, granular, running from base of epibranchial tooth to epimeral sulcus. Epistomial tooth triangular, defl exed, edges smooth. Exopod of third maxilliped long, reaching ischium/merus junction, fl agellum of exopod long, ischium with deep vertical groove. Mandibular palp 2-segmented with small, hard, rounded lobe at junction between segments, lobe one-third length of terminal segment. s1/s2 short, very faint; s2/s3 deep, wide, completely crossing sternum; s3/s4 incomplete, faint in middle deep at sides. Episternal sulci s4/e4, s5/e5, s6/e6, s7/e7 absent. Male abdomen triangular, tapered, widest at a3, narrowest at a7 (telson); telson outline forming straight-sided triangle with broad base, rounded apex. Sternal grooves s4/s5 meeting telson just beyond abdominal groove between a7/a6; sternal grooves s5/s6 meeting a6 one half somite length from a6/a5; sternal grooves s6/s7 meeting a5 one third somite length from a5/a4. G1 terminal article short (ratio of length of terminal article to subterminal segment 0.27), cone-shaped, straight, tapering to broad tip, apical opening narrow, directed slightly outward, smooth; mid-proximal portion of G1 terminal article widened laterally by rounded lobe; lateral, medial folds basally separated, meeting midway along ventral face, forming longitudinal groove that continues almost to tip of article; groove not visible on dorsal face. Subterminal segment of G1 with raised rounded shoulder on lateral margin near junction with terminal article. Terminal article/subterminal segment junction of G1 marked by faint diagonal line on ventral side, dorsal side marked by broad, subtriangular dorsal membrane; superior margin of dorsal membrane formed by horizontal basal margin of terminal article, inferior margin of membrane formed by U-shaped distal edge of subterminal segment; lateral, medial margins of dorsal membrane narrow. Terminal article of G2 fl agellum-like, long, reaching anterior margin of sternoabdominal cavity; fl agellae of G2 viewed together in situ forming heart shape; distal parts of terminal articles of both G2s touching, sometimes protruding from under closed abdominal telson.
Movable fi nger (dactylus) of major (right) cheliped slender, upper margin smooth. Fixed fi nger long, ⅓ height of palm; lower margin of palm slightly indented; proximal region of cutting edge of fi xed fi nger with four large, fused molars followed distally by series of small teeth. Carpus with two teeth on inner margin, fi rst tooth large, pointed, second tooth smaller, pointed, followed by series of very small teeth. Medial, lateral margins of inferior face of cheliped merus distinctly toothed, inferior face with pointed, granulated, distal tooth; superior margin and superior face of merus covered with granules and short carinae; granules on medial margin of merus continuous with granules on medial margin of cheliped ischium, inferior margin of ischium rounded, smooth. Walking legs (p2-p5) of normal length, not strikingly elongated, inner margins of propodi of p2 to p5 smooth.

Size
The largest known specimen is the male holotype, CW 43.7. Adults judged by size at pubertal molt are between CW 37 and CW 42.

Distribution
Foza manonae sp. nov. is known only from two localities in Antsiranana Province in northern Madagascar: Ankarana Special Reserve and Montagne des Français Reserve (Fig. 4).

Ecology
At the Ankarana Special Reserve the new species is found in sympatry with two other species of freshwater crabs: Foza ambohitra (ZSM A20145001, ZSM A20145002) and Madagapotamon humberti (ZSM A20145007, ZSM A20145008, ZSM A20145009, ZSM A20145010). Foza manonae sp. nov. is also found in sympatry with M. humberti (ZSM A20145012) at Montagne des Français Reserve, where the two species were caught together in pitfall traps. Both F. ambohitra and M. humberti are known to be semi-terrestrial air-breathing crabs (Cumberlidge & Meyer 2009), so it is likely that F. manonae sp. nov. also has similar habits and abilities, and also has a similar degree of independence from permanent water sources. Furthermore, the branchial chambers of F. manonae sp. nov. (like those of F. ambohitra) each house two different sets of respiratory organs: a dorsal pseudolung for aerial respiration and ventral gills for aquatic respiration (Sternberg & Cumberlidge 2001).

Remarks
The differences between Foza and the other Malagasy freshwater crab genera are discussed by Reed & Cumberlidge (2006), Meyer (2009), andMeyer et al. (2014). Foza manonae sp. nov. is assigned to the genus Foza on the basis of characters that it shares with F. raimundi Reed & Cumberlidge, 2006, the type species of the genus (Reed & Cumberlidge 2006). These characters include a bilobed mandibular palp, a faint postfrontal crest, sternal grooves s6/s7 that meet the margin of abdominal segment a5 in the middle of the segment, and curved, elongated G2s that together form a distinctive heart shape ( Fig. 2A). A preliminary DNA comparison of 16S rRNA sequences of F. manonae sp. nov. with those of other Malagasy freshwater crab species available from GenBank was made by the second author (SK, unpublished data). The results positioned the new species in a separate clade, although the taxonomic sampling and exact identity of the species to which the other sequences belong is currently the focus of a larger molecular phylogenetic study of the Malagasy freshwater crab fauna using a wider range of molecular markers (S.R. Daniels, pers. comm.).
The four species of Foza are compared in Table 1 and can be identifi ed as follows: Foza manonae sp. nov. can be distinguished from F. raimundi Reed & Cumberlidge, 2006 by the texture of the anterolateral surfaces of the carapace (which have heavy carinae in F. manonae sp. nov. but are smooth, or with only a few light carinae in F. raimundi), by the texture of the suborbital and subhepatic regions of the carapace sidewall (which have granules and/or carinae in F. manonae sp. nov. but are smooth in F. raimundi), by the terminal article of G1 (which is cone-shaped in F. manonae sp. nov. and tube-shaped in F. raimundi), by the pterygostomial region and the sternoabdominal cavity (which largely lack setae in F. manonae sp. nov. but have dense fi elds of setae in F. raimundi), and by the sternal sulcus s3/s4 (which is incomplete and only visible at the sides in F. manonae sp. nov., but complete and crossing the entire thoracic sternum in F. raimundi).
Foza manonae sp. nov. can be distinguished from F. ambohitra by the texture of the posterolateral corners of the carapace (which have heavy carinae in F. manonae sp. nov., but are smooth with a few light carinae in F. ambohitra), by the texture of the suborbital and subhepatic regions of the carapace sidewall (which have granules and/or carinae in F. manonae sp. nov., but are smooth in F. ambohitra), by the suborbital and subhepatic regions of the carapace sidewall (which are granulated in F. manonae sp. nov., but smooth in F. ambohitra), and by the terminal article of G1 (which is widened in F. manonae sp. nov., but slim and evenly tapered in F. ambohitra).
Foza manonae sp. nov. can be distinguished from F. goudoti by the postfrontal crest (which is faint and incomplete in F. manonae sp. nov., but distinct and completely crosses the carapace in F. goudoti), by the anterolateral surfaces of the carapace (which have heavy carinae in F. manonae sp. nov., but are

Distribution
This species was described by Cumberlidge & Meyer (2009) from specimens collected in Antsiranana Province, northern Madagascar, at Ambohitra (formerly Joffreville) in the Diana Region, and at two localities in the Analamerana Special Reserve. The present report adds a new locality for this species: the Ankarana Special Reserve (Fig. 4). In light of the new material and preliminary DNA analysis, it is possible that the specimen from Toamasina Province, Montagne d'Akirindro (NMU PN 17-21.3.2003), included in F. ambohitra by Cumberlidge & Meyer (2009), may not prove to belong to this species (S.R. Daniels, pers. comm.).

Remarks
Foza ambohitra is a medium-sized species that lives in the mixed dry deciduous and humid forests of northern Madagascar. The species can be recognized by its anterolateral margins (granular), its carapace sidewalls (completely smooth except for a small fi eld of granules at the junction of the longitudinal and vertical sutures), and by its sternal sulcus s3/s4 (which is complete, U-shaped, and does not meet the sternoabdominal cavity).
The material reported on here also includes two small juvenile crabs (CW 9.5, CL 7.6 and CW 9.0, CL 7.2) (ZSM A20145014) from the Ankarana Special Reserve that are diffi cult to identify because their morphology includes a number of characters that have yet to develop to the adult form. Nevertheless, these specimens clearly belong to the genus Foza and were collected at the same locality as the specimens of F. ambohitra (ZSM A20145001, ZSM A20145002). However, we hesitate to assign these juvenile specimens to F. ambohitra because they possess dense fi elds of setae on the anterior pterygostomial region of the carapace sidewall, and because they have very elongated walking legs, both of which are characters that would place them close to F. raimundi.

Remarks
Madagapotamon humberti is one of the most distinctive species of all of the Madagascan freshwater crabs and this colorful, long-legged, rock-crevice and cave-dwelling species stands apart from all others on the island. M. humberti can easily be distinguished by the absence of a fl agellum on the exopod of the third maxilliped, by the mandibular palp with a simple terminal segment, and by the egg-shaped outline of the adult male abdomen. Living specimens from the Ankarana Special Reserve have a yellow carapace, pink legs, and chelipeds with white fi ngers, while those from Montagne des Français Reserve have an all-white carapace, along with pink legs and chelipeds with white fi ngers.  (Table 2). Two species (Boreathelphusa uglowi (Cumberlidge & Sternberg, 2002) and  were found to be vulnerable to extinction (VU) and another fi ve (Malagasya goodmani Cumberlidge, Boyko & Harvey, 2002; Marojejy longimerus (Cumberlidge, Boyko & Harvey, 2002); Skelosophusa gollhardi (Bott, 1965); S. prolixa Ng & Takeda, 1994;S. eumeces Ng & Takeda, 1994) were Data Defi cient (DD) -i.e., they were too poorly known to even carry out a conservation assessment (Cumberlidge 2008a(Cumberlidge , 2008b.

Conservation status of Malagasy freshwater crabs
The fi ve Malagasy DD species of freshwater crabs (35% of the fauna) introduce an element of uncertainty into the conservation planning process because their conservation status (when assessed) may either increase or decrease the number of threatened species (VU, EN, or CR), or it may not change current estimates if all of these species prove to be LC. However, it is likely that most of the DD species will be assessed as belonging to a threatened category because many of the DD species are single-locality endemics with a very narrow distributional range, a profi le typical of many of the species currently in threatened categories worldwide ). For example, Sri Lanka is one of the few countries where the conservation status of the entire freshwater crab fauna has been assessed, and its faunal list therefore includes no DD species (Bahir et al. 2005;). These studies show that Sri Lanka has the highest number of threatened species of freshwater crabs of any country in the world and that many of these species are single-locality endemics ). Clearly, the VU and DD species of endemic Madagascan freshwater crabs present obvious foci for future ecological fi eldwork, biotic inventories, and conservation prioritization activities.
The specimens reported on here (Fig. 4)  The conservation status of F. ambohitra, F. manonae sp. nov., and one species of Glabrithelphusa Meyer et al., 2014 has not yet been assessed because these taxa were described since the IUCN global conservation assessment was carried out ). The specimens of M. humberti (VU) reported here from near the Baie de Sakalava and from the Orangea Reserve are new locality records for this species, and the specimens from the Montagne des Français Reserve confi rm its continued presence after more than 110 years. These new data may well infl uence the current conservation status of   (Cumberlidge & Meyer 2009), and will be useful when the conservation status of this species is eventually assessed.