Bioacoustics of Echinoderes multiporus

Remarks. Based on the spine and tube pattern having middorsal acicular spines only on segments 4, 6, and 8, lateroventral acicular spines on segments 6–9, ventrolateral tubes on segment 2, lateroventral tubes on segment 5, and midlateral tubes on segment 10, and lacking lateral accessory tubes on segment 8, Echinoderes multiporus sp. nov. is similar to E. bermudensis Higgins, 1982 , E. joyceae Landers & Sørensen, 2016 , and Echinoderes apex Yamasaki et al., 2018 ( Higgins 1982 ; Landers & Sørensen 2016 ; Yamasaki et al . in press). However, the new species can be easily distinguished from the above mentioned three species by the presence of type-2 glandular cell outlets on segments 2 and 3–9 (type-2 glandular cell outlets are present on segments 2, 6, and 8 in E . joyceae and the undescribed species, but absent in E. bermudensis ). Echinoderes multiporus sp. nov. is the only Echinoderes species with the laterodorsal type-2 glandular cell outlets on most of the segments. The presence of only two pairs of penile spines found in males of Echinoderes multiporus sp. nov. is also the rare character among the congeners. Males of Echinoderes species usually have three pairs of penile spine, whereas two pairs of penile spines have been found in the following ten species together with E. multiporus sp. nov. : Echinoderes . aureus Adrianov et al ., 2002 ; Echinoderes . astridae Sørensen, 2014 ; Echinoderes . cavernus Sørensen et al ., 2000; Echinoderes kristenseni Higgins, 1985 ; Echinoderes lanceolatus Chang & Song, 2002; Echinoderes newcaledoniensis Higgins, 1967 ; Echinoderes . marthae Sørensen, 2014 ; Echinoderes maxwelli (Omer-Cooper, 1957) ; Echinoderes remanei (Blake, 1930) ; and Echinoderes . rex Lundbye et al ., 2011 (see Higgins 1964 , 1967 , 1985 ; Sørensen et al . 2000; Adrianov et al . 2002; Chang & Song 2002; Lundbye et al . 2011 ; Sørensen 2014 ). Despite the presence of only two pairs of penile spines in these species, the species do not agree in most of the other morphological characters, i.e., the shape and the patterns of spines, tubes, and type-2 glandular cell outlets. It can be supposed that only two pairs of penile spines evolved repeatedly independently within the genus. However, the morphological evolution of Echinoderes is still open to question due to the lack of knowledge about the phylogenetic relationships within the genus.