Achelous rufiremus ( Holthuis, 1959 )

Rodrigues, Iana Barbosa & Serejo, Irene Azevedo Cardoso and Cristiana Silveira, 2017, Catalogue and illustrated key of Achelous De Haan, 1833 and Portunus Weber, 1795 (Brachyura: Portunidae: Portuninae) species occurring in Brazilian waters, Nauplius (e 2017005) 25, pp. 1-12 : 3-5

Achelous rufiremus ( Holthuis, 1959)

( Fig. 2C )

Material examined. # 313, Brazil, Amapá, Amazonas River , 01°46’S 48°21’W, 46–47 m, mud bottom, 1 male (cw 2.5; cl 1.6), MNRJ 301 .

Diagnosis. Carapace densely granular and pubescent; granules rather evenly distributed, but forming two distinct transverse rows in the gastric area: one on the line between meso- and meta-gastric regions, and one somewhat more anteriorly and interrupted in the middle; naked spot near postero-lateral margin. Frontal region with six teeth;median teeth bluntly triangular or rounded and separated from one another by a U-shaped sinus; submedian teeth very broad at the base and a top bluntly rounded, separated from median teeth by a very wide sinus, and from lateral frontal teeth 1 by a much narrower sinus; median teeth and submedian teeth about equally far forwards, slightly overreaching lateral frontal teeth 1. Posterior anterolateral tooth very strong, distinctly more than twice as long as the preceding and directed straight outwards. Chelipeds very long, pubescent and with granular carinae; merus with four to six strong spines on inner margin and one at the distal end of outer margin; upper surface bearing granules and short hairs; carpus with two strong spines on anterior margin, one in the inner and one in the outer part. Merus of swimming legs about as long as broad; posterior margin with distinct spine (modified from Holthuis, 1959).

Measurements. Only record of one male belonging to the MNRJ: cw 25, cl 16.

Color. Preserved specimens: carapace pale reddish brown. Legs still paler reddish brown above. Lower surface is yellowish white. Spines on inner margin of the merus of chelipeds are dark red, as are also the inner spine of carpus and tips of fingers. Distal joints of second to fourth pereopods are pinkish, while distal half of dactylus of the swimming legs has a dark red spot ( Holthuis, 1959).

Geographic distribution. Western Atlantic: Guyana, Brazil (Amapá, Pará and Maranhão) ( Melo, 1996; Viana et al., 2003).

Type locality. Between mouths of the Suriname and Marowijne Rivers , 6°44’N 54°31’W; mud bottom; depth 42 m.

Habitat. At depths of 20 m to 45 m, on mud, shells and coral bottom ( Holthuis, 1959).

Figures

Figure 2. A,Achelous gibbesii, DOUFPE 7120; B,Achelous ordwayi, MNRJ 16244; C, Achelous rufiremus, MNRJ 301.Scale bars:2cm.