Potamonautes bellarussus, Daniels & Phiri & Bayliss, 2014

Daniels, Savel R., Phiri, Ethel E. & Bayliss, Julian, 2014, Renewed sampling of inland aquatic habitats in southern Africa yields two novel freshwater crab species (Decapoda: Potamonautidae: Potamonautes), Zoological Journal of the Linnean Society 171 (2), pp. 356-369 : 361-363

POTAMONAUTES BELLARUSSUS SP. NOV.

( FIGS 3 , 4A–C , 5A–C )

Holotype: One male specimen (SAM A 48212), Yao Mountain, 1045 m a.s.l., 12°27′36″ S, 36°32′42″ E, Niassa province, northern Mozambique, collected on 13 May 2012 by Julian Bayliss. Specimens were collected from bolderstrewn mountain streams in a mixed riverine/woodland habitat close to the summit.

Paratype: One male specimen (SAM A 48213), Yao Mountain, with the same collection information as the holotype.

Additional material examined: One female (SAM A 48217), Yao Mountain, 1045 m a.s.l., 12°27′36″ S, 36°32′42″ E, Niassa province, northern Mozambique, collected on 13 May 2012 by Julian Bayliss, one female (SAM A 48218), Yao Mountain , 1045 m a.s.l., 12°27′36″ S, 36°32′42″ E, Niassa province, northern Mozambique, collected on 13 May 2012 by Julian Bayliss ; three females from the Mecula Mountain , Niassa province, 1046 m a.s.l. (SAM A 48214, A 48215, and A 48216), at 12°43′39″ S, 37°38′49″ E, northern Mozambique, collected on 9 May 2012 by Julian Bayliss .

Diagnosis: Flat freshwater crab species, postfrontal crest deep and well defined, exorbital tooth prominent, anterolateral margins granulate ( Figs 3 , 4A–C ). Carapace, periopods, chelipeds blood red when alive (colour faded in preserved specimens).

Description: See Table 2 for the measurements of the holotype. Postfrontal crest deep, distinct, crossing the entire carapace, groove at posterior part of carapace deep. Colour faded in preserved specimens. Carapace flat (CWW/ CH = 3.07), narrow posteriorly (CWP/ CL = 0.44). Exorbital epibranchial tooth prominent, anterolateral margin behind epibranchial tooth heavily granulated. Anterolateral margins heavily granulat- ed, urogastic and cardiac regions deep, well-defined, subhepatic region of carapace sidewall faintly granulated. Sternites of sulcus s3/s4 well defined. Dactylus of major cheliped with series of well-defined teeth, dactylus not arched, tips white. First carpal tooth on carpus of cheliped with large prominent and sharp spine, second carpal tooth smaller, third small carpal tooth behind the second tooth is present but reduced in size. Terminal article of gonopod 1 long, slim, curving to the right, and comprising nearly half of gonopod 1 and nearly half of the length of gonopod 1 ( Fig. 5A, B ). Gonopod 2 is thin, long, and filamentous, with the terminal article long and slender, and with a slight curve ( Fig. 5C ).

Distribution: Endemic to Mecula and Yao Mountains in the Niassa province of northern Mozambique.

Remarks: Potamonautes bellarussus sp. nov. resembles P. suprasulcatus in morphology. Telphusa suprasulcata var. pseudoperlata (Hilgendorf, 1898) and Telphusa mrogoroense (Hilgendorf, 1898) are considered here to be junior subjective synonyms of mountain streams whereas P. suprasulcatus lives in major rivers ( Reed & Cumberlidge, 2006).

The novel Mozambican freshwater crab species was also phylogenetically distantly related to the six described freshwater crab species from Mozambique ( P. bayonianus , P. choloensis , P. calcaratus , P. obesus , P. namuliensis , and P. sidneyi ). Notably, the four east African freshwater crab species present in Mozambique ( P. choloensis , P. calcaratus , P. obesus , and P. namuliensis ) formed a distinct basal clade. The two remaining species ( P. bayonianus and P. sidneyi ), characterized by wide distribution ranges in southern Africa, belonged to a clade comprising the large-bodied freshwater crab species. Superficially, P. bellarussus sp. nov. also resembles Potamonautes unisulcatus (Rathbun, 1933) . The latter species is endemic to the Uluguru Mountains in northern Tanzania, and gonopod 1 of P. bellarussus sp. nov. is different from P. unisulcatus ( Reed & Cumberlidge, 2006) . In addition, in P. bellarussus sp. nov. three carpal teeth are present, whereas in P. unisulcatus only two teeth are present.

Etymology: The name P. bellarussus sp. nov. is an arbitrary combination of two aspects. ‘Bellus’ is Latin for beautiful, and is in honour of Dr Bella Davies for her dedication to freshwater ecology in the UK and Africa, whereas the Latin ‘russus’ refers to the blood-red colour of living specimens. The name is used as a noun in apposition.

Figures

Figure 3. Potamonautes bellarussus sp. nov., female from the Mecula mountains in the Niassa province, Mozambique, showing the bright-red colour of the freshwater crab while alive.

Figure 4. Potamonautes bellarussus sp. nov., male holotype (carapace length = 39.29 mm) from the Yao Mountains, 1045 m a.s.l., 12°27′276″ S, 36°32′260″ E, Niassa province, Mozambique (SAM A 48212): A, whole animal, dorsal aspect; B, whole animal, ventral aspect; C, cephalothorax, frontal aspect. Scale bars: 10 mm.

Figure 5. Potamonautes bellarussus sp. nov., male holotype from the Yao Mountains, Niassa province, Mozambique (SAM A 48212): A, left gonopod 1, anterior view; B, left gonopod 1 posterior view; C, left gonopod 2 anteri- or view. Scale bars: 10 mm.