Ricstygnus, Kury, Adriano B., 2009

Kury, Adriano B., 2009, A new genus of Stygninae from a relictual rainforest in Ceará, northeastern Brazil (Opiliones, Laniatores, Stygnidae), Zootaxa 2057, pp. 63-68 : 64

Ricstygnus gen. nov.

Etymology. The genus name is a composite of Ric, a homage to my friend Ricardo Pinto-da-Rocha, who published the only monographic treatment of the Stygnidae to date, plus Stygnus , the type genus of the family, and should be treated as being masculine in gender.

Type species. Ricstygnus quineti sp. nov.

Diagnosis. Differs from all other Stygninae by: (1) presence of dorso-basal hollow in ventral plate containing a multiply folded haematodocha (instead of absence); (2) distal part of ventral plate forming roof with 2 straight prongs (instead of smooth, without roof); (3) intermediate setae of ventral plate short and situated dorsally (instead of usually long and laterally placed, but see Pinto-da Rocha, 1997 figs. 574 and 577 for exceptions in Sickesia and Protimesius ); (4) scutal armature consisting of 1 pair of paramedian acuminate tubercles on each area III to posterior margin (instead of 1 pair of tubercles on area III); (5) main armature consisting of 1 pair of paramedian acuminate spines on free tergite I (instead of armature of free tergites stouter at free tergite III); (6) scutum outline subtrapezoid, widest at posterior border with 2 constrictions (instead of subrectangular, narrowest at posterior border); (7) carapace as long as abdominal scutum (instead of clearly shorter); and (8) scutal groove deeply projected into area I separating it into 2 triangular halves and reaching groove II (instead of not reaching groove 2 and causing much smaller deformation of area I). The combination of (9) presence of cornute macrosetae, consisting of 3 pairs of large, flattened curved distal macrosetae of ventral plate and (10) basal setae of ventral plate clearly transverse instead of oblique, relates Ricstygnus gen. nov. to Stygnus , Sickesia (distal macrosetae normal) and Pickeliana . The presence of interocular stout spine (11) suggests that it is probably closest to Stygnus and Sickesia .