Palaeobenthesicymus, Audo & Charbonnier, 2013

Audo, Denis & Charbonnier, Sylvain, 2013, Late Cretaceous crest-bearing shrimps from the Sahel Alma Lagerstätte of Lebanon, Acta Palaeontologica Polonica 58 (2), pp. 335-349 : 340

Genus Palaeobenthesicymus nov.

Etymology: From Latin palaeo, ancient, and benthesicymus, modern genus that means “inhabitant of depth” after Bate (1888).

Type species: Penaeus libanensis Brocchi, 1875 ; Sahel Alma Lagerstätte , upper Santonian, Lebanon .

Diagnosis.—Subrectangular cephalothorax with very short rostrum; hypertrophied rostral crest, laterally compressed, obliquely triangular and very thin; bilobed eyes; very narrow cervical groove, intercepting dorsal margin posterior to the crest; short antennal groove; postcervical groove weakly marked, joined to branchiocardiac groove; well−marked branchiocardiac groove curved anteriorly, limited by two parallel ridges, joined to hepatic groove; short hepatic groove; well−marked longitudinal ridge, sub−parallel to the ventral margin, joined to branchiocardiac and hepatic grooves; s5 and s6 dorsally carinate; uropodal exopod with diaeresis.

Discussion.— Palaeobenthesicymus gen. nov. differs from the extant Benthesicymus Bate, 1881 , as follows: the configuration of the cephalothoracic grooves, the subcomplete reduction of the rostrum, the absence of rostral teeth, the presence of bilobed eyes and, the diaeresis on the uropodal exopods. For the same reasons, the new genus differs also from the other genera of Benthesicymidae : Gennadas Bate, 1881 , Bentheogennema Burkenroad, 1936 , Benthonectes Smith, 1885 , and Altelatipes Crosnier and Vereshchaka, 2008 . However, Palaeobenthesicymus gen. nov. has different morphological characters such as the very thin, soft and flexible cuticle, the short rostrum, the rostral crest and, the configuration of the cephalothoracic grooves, which are typical of Benthesicymidae , justifying its ascription to this family.

Stratigraphic and geographic range.—Upper Santonian, Upper Cretaceous, (after Ejel and Dubertret 1966), Nannofossil Biozone UC13 Burnett, 1998 —UC17 pro−parte Sissingh, 1977 (Silvia Gardin, personal communication 2010), Sahel Alma Lagerstätte ( Lebanon, Middle East).