Phyllocheres Humes, 1996

Phyllocheres Humes, 1996 View in CoL

Emended diagnosis. Asterocheridae . Body cyclopiform. Prosome 4-segmented in female, 5-segmented in male. Antennule 18- to 20-segmented in female with aesthetasc on segment 17; ancestral segments IX–XIII fused; distal 3 segments frequently fused to become 1 or 2 segments. In males, 17 or 18-segmented with aesthetasc on segment 15 to 17, and ancestral segments IX-XIII are fused. Exopod of antenna 1-segmented; 3-segmented endopod with terminal segment bearing distal claw. Oral cone short or elongated, siphon-like. Mandible consisting of stylet and 1- or 2-segmented palp bearing two distal setae. Maxillule bilobed. Maxilla 2-segmented; distal segment forming curved claw. Maxilliped 5- or 6-segmented, sexually dimorphic, with medial prominence on second segment. Legs 1-4 biramous, with both rami 3-segmented; second segment of endopods with 2,2,2,2. Leg 5 with free segment bearing 2 or 3 setae.

Remarks. The antennule has a well-defined condition regarding the proximal region by exhibiting the fused segment composed of the ancestral segments IX-XIII. the original diagnosis of Neoasterocheres proposed by Canário et al. (2017) defines the maxilliped as 6-segmented, as seen in on N. breviseta Canário et al., 2017 , however, N. humesi Varela, 2012 , N. scutatus Stock, 1966 , N. serrulatus Humes, 1996 , N. dysideae Humes, 1996 , N. enewetakensis Humes, 1997 , N. rotundus Malt, 1991 exhibit a 5-segmented maxilliped. As Phyllocheres also has a 5-segmented maxilliped ( Humes, 1996a), the diagnosis of the maxilliped now acknowledges this variation.

Additionally, Asterocheres spongus Johnsson, 2002 , species treated as inquirendum by Kim (2010) in his redefinition of Asterocheres , also exhibits the ninth antennule segment composed of the fused ancestral segments IX–XIII, with the aesthetasc on the 17th segment, plus a terminal segment and a 5-segmented maxilliped. By presenting this set of features, this species should also be reassigned to the genus Phyllocheres as P. spongus ( Johnsson, 2002) .

Type species by original designation: Phyllocheres petalus Humes, 1996

Other species:

P. breviseta ( Canario, Rocha, Neves & Johnsson 2017) comb. nov.

P. dysideae (Humes 1996) comb. nov.

P. enewetakensis ( Humes 1997) comb. nov.

P. humesi ( Varela 2012) comb. nov.

P. rotundus ( Malt 1991) comb. nov.

P. scutatus (Stock 1966) comb. nov.

P. serrulatus (Humes 1996) comb. nov.

P. spongus ( Johnsson, 2002) View in CoL comb. nov.

Phyllocheres petalus View in CoL shares the 19-segmented female antennule with aesthetasc on the 17th segment with seven congeners: P. breviseta ( Canário, Rocha, Neves & Johnsson, 2017) , P. dysideae (Humes, 1996) , P. enewetakensis ( Humes, 1997) , P. humesi ( Varela, 2012) , P. rotundus ( Malt, 1991) , P. scutatus (Stock, 1966) , and P. serrulatus (Humes, 1996) .

Phyllocheres petalus View in CoL can be differentiated from P. breviseta , P. humesi , and P. rotundus by exhibiting three setae on the antennal exopod, while those species exhibit only two setae ( Malt 1991; Varela 2012; Canário et al. 2017). The mandibular palp on P. petalus View in CoL , is 2-segmented, differing from P. scutatus , which is 1-segmented ( Stock 1966a). And ultimately, P. petalus View in CoL exhibits three equally sized setae on the free segment of leg 5, differing from P. dysideae , P. spongus View in CoL , and P. enewetakensi , which show three unequally-sized setae, and also from P. serrulatus , which shows only two equally sized setae ( Humes 1996a; 1996b; Humes 1997; Johnsson 2002; Canário et al. 2017).

Phyllocheres petalus View in CoL exhibits produced epimera on both posterolateral margins of the cephalosome, reaching beyond the anterior margin of the genital somite in both sexes, creating a half-moon-shaped cephalosome as an exclusive feature for the species.