"A new species of Foza Reed & Cumberlidge, 2006, From Northern Madagascar"

Foza ambohitra sp. n. is described from Ambohitra, Antsiranana Province, northern Madagascar at 421 m elevation. Th is species is distinguished by characters of the carapace, the male anterior thoracic sternum, and the form of the male major cheliped and fi rst gonopod. Th elphusa goudoti H. Milne Edwards, 1853, is transferred to Foza Reed & Cumberlidge, 2006, and redescribed, and a key to the three species of this genus is provided. Comments on the rare cave crab Skelosophusa prolixa Ng & Takeda, 1994, from Antsiranana Province are also included based on newly obtained material.


Introduction
Th e present work reports on the discovery of a new species of freshwater crab, Foza ambohitra, from Antsiranana Province in northern Madagascar, from material obtained over a number of years by diff erent collectors. In addition, Hydrothelphusa goudoti (H. Milne Edwards, 1853) is redescribed and reassigned here to Foza Reed & Cumberlidge, 2006, and a key to the three species of this genus is provided. We also describe new characters of the rare cave crab Skelosophusa prolixa Ng & Takeda, 1994, and provide habitus photographs of a large adult male specimen.

Material
Th e material is housed in the collections listed below:

Methods
All measurements were made with digital calipers, and are given in millimetres. Carapace width (CW) is the distance across the carapace at the widest point; the carapace length (CL) is measured along the median line, from the anterior to the posterior margin; the carapace height (CH) is the maximum height of the cephalothorax from the highest point of the gastric region to the suture between thoracic sternites s2 and s3; the front width (FW) is measured along the anterior frontal margin between the base of the orbits. Th e following abbreviations are used: a1-a6, abdominal somites 1-6; a7, telson of abdomen; asl, above sea level; e, thoracic episternite; s4/e4, s5/e5, s6/e6, s7/ e7, episternal sulci between respective thoracic sternites and episternites thoracic sternite; GO1, fi rst gonopod; GO2, second gonopod; p1-p5, pereiopods 1-5; s4/s5, s4/ s5, s5/s6, s6/s7, s7/s8, sternal sulci between respectively numbered thoracic sternites. Th e terminology is adapted from Cumberlidge (1999). Line drawings were prepared using a Leica MZ 16 stereobinocular microscope. Photographs were taken with a digital camera in combination with an eyepiece adapter. Post processing was done in Adobe Photoshop 7.0. Diagnosis. Anterolateral margin lined by small granules. Suborbital, subhepatic, pterygostomial regions smooth with small fi eld of granules at junction of longitudinal, vertical sutures. Outer face of merus of cheliped (pereiopod 1) smooth, granules present on upper margin only. Sternal sulcus s3/s4 complete, U-shaped, not meeting sterno-abdominal cavity. Terminal article of GO1 short, slim, tapered, with distinct raised rounded shoulder on external margin, slightly lower than junction with terminal article.
Description. Based on holotype, adult male. Carapace outline transversely oval, very high (CH/FW 1.90); front narrow (FW/CW 0.22), defl exed; epibranchial tooth small, pointed, advanced in position, almost touching exorbital tooth; anterolateral margin evenly curved outward, lined by small granules, continuous with posterolateral margin, latter margin with faint or absent striae; postfrontal crest faint to absent, epigastric crests faint, positioned forward on front almost touching frontal margin, postorbital crests faint; deep mid-groove between epigastric crests forked posteriorly; cardiac, urogastric grooves faint, semicircular grooves deep; cervical grooves faint, long, not meeting postorbital crest. Suborbital region of carapace smooth, subhepatic region smooth, pterygostomial region smooth except for setae on lower margin, small fi eld of granules at junction between longitudinal, vertical sutures; vertical sulcus on carapace sidewall curved, granular, running downward from base of epibranchial tooth to epimeral sulcus.
Dactylus of both chelipeds relatively slender, approximately one-third height of palm, edges smooth except for 2 distinct teeth, one positioned basally, one half way along; upper margin of dactylus smooth; lower margin of propodus slightly indented. Fixed fi nger of propodus of major (right) cheliped slender with 3 large molars in proximal region (fi rst 2 fused basally, third single) followed by series of small teeth. First carpal tooth on inner margin of carpus of cheliped large, pointed; second carpal tooth smaller, pointed, followed by a large granule. Medial, lateral margins of inferior face of merus of cheliped distinctly toothed, inferior face with pointed, granulated distal meral tooth; superior margin of merus of cheliped roughened by granules and short striae; outer face of merus smooth; granules on medial margin of merus, ischium of cheliped smooth, inferior margin of ischium rounded, smooth. Walking legs (p2-p5) elongated (ratio of merus length of p5 to CW 0.3), slender, inner margins of p2 to p5 propodi smooth. Male abdomen triangular, tapered distally, widest at a3, narrowest at a7 (telson); telson outline forming straightsided triangle with broad base, rounded apex.
Terminal article of GO1 short (ratio of length of terminal article to subterminal segment 0.25), slim, tapered, directed slightly outwards, straight, smooth, apical Comparisons. Foza ambohitra, sp. n., is assigned to the genus Foza on the basis of characters that it shares with F. raimundi Reed & Cumberlidge, 2006, the typespecies of the genus (Reed and Cumberlidge, 2006). Th e two species share a weak postfrontal crest, a narrow frontal margin of the carapace (FW/CW 0.22 F. ambohitra, 0.25 F. raimundi) and a GO2 terminal article that curves inward distally; and the epibranchial tooth of both species is in a forward position, almost touching the exorbital tooth. Foza ambohitra can be distinguished from F. raimundi as follows: the terminal article of GO1 of F. ambohitra is cone-shaped and tapered ( Fig. 2A), while that of F. raimundi is tube-shaped (Reed and Cumberlidge, 2006: Fig. 2B-D); both the superior part of the pterygostomial region and the sterno-abdominal cavity of F. ambohitra lack setae (Fig. 1D, 2C), whereas setae are present in these regions in F. raimundi; the anterolateral margin of F. ambohitra is granular and the posterolateral margin is smooth (Fig. 1A), whereas the anterolateral margin of F. raimundi is smooth and the posterolateral margin is carinated (Reed and Cumberlidge, 2006: Fig. 1B); and the major cheliped of F. ambohitra has three large molars (Fig. 1E) whereas that of F. raimundi has one large fused molar (Reed and Cumberlidge, 2006: Fig. 1E). Th e three species of Foza are compared in Table 1. Th e diff erences between Foza and the other Malagasy freshwater crab genera are discussed by Reed and Cumberlidge (2006).
Etymology. Ambohitra is the modern name of Joff reville, a French colonial town in northern Madagascar, near where the specimens described here were collected. Ambohitra is a noun in apposition.
Habitat. Partially disturbed mixed dry deciduous and humid forest in northern Madagascar.
Comparisons. Cumberlidge and Sternberg (2002) assigned T. goudoti to Hydrothelphusa on the basis of its bilobed mandibular palp, but commented on the diff erences in a number of other characters of the carapace between this species and the others included in that genus. For example, the exorbital and epibranchial teeth of F. goudoti are both low and blunt and positioned close together, and the carapace is very wide (CW/FW 3.9) and highly arched (CH/FW 1.6). In the other species of Hydrothelphsua these teeth are large and well spaced, and the carapace is not noticeably widened or infl ated ( Cumberlidge and Sternberg, 2002). Th is taxon is transferred here to the genus Foza because it shares a number of important taxonomic characters with both F. raimundi and F. ambohitra (Table 1). Remarks on Skelosophusa prolixa Ng and Takeda, 1994 (Fig. 4) Th e fi rst author discovered fi ve specimens from northern Madagascar in the unidentifi ed collection of the NHM (NHM 2009.119, NHM 2009.120 -121, NHM 2009.122, NHM 2009.123, NHM 2009) that proved to belong to Skelosophusa prolixa. All of these specimens were collected from Riviére Cave, Cañon Forestier, Ankarana, 60 km south of Diego Suarez, northern Madagascar, 8 August-27 September 1986, by N. W. Lear and S. U. Fowler. Although the locality is similar to that reported for the holotype, it may be possible that these specimens are topotypic, and were collected at the same time as the original type series. However, it is diffi cult to be certain of this because the date of collection and the names of the collectors were not supplied in the original description (Ng and Takeda, 1994). Skelosophusa prolixa was previously known only from two specimens collected from this same locality. Th e holotype described by Ng and Takeda (1994) has a CW of 25.6 mm and CL of 18.8 mm; these two measurements give a cw/cl ratio of 1.3 (compared to 1.4 for the present specimens). Th is species possesses a number of adaptations (e.g. normal length eyestalks but with reduced corneas, lack of pigmentation of the carapace and legs, and extremely long ambulatory legs, p2-p5) typical of true cave-adapted species of freshwater crabs (Ng and Takeda, 1994). Th e adult male specimen among the new material photographed here (Fig. 4A-D) (CW 29.3 mm) is larger than the holotype male (CW 25.6 mm) and shows characters of the cheliped that have not previously been described. For example, the immovable fi nger of the major cheliped of S. prolixa has one large, fused molar tooth in adults, whereas that of the holotype male, a smaller specimen, has only small teeth (Ng and Takeda, 1994).