A new genus for “Neocallichirus” grandis Karasawa & Goda, 1996, a ghost shrimp species (Decapoda: Axiidea: Callianassidae) heretofore known only by fossil materials

Abstract

A new genus of the family Callianassidae, Laticallichirus, is established for “Neocallichirus” grandis Karasawa & Goda, 1996, a ghost shrimp species heretofore represented only by fossil materials from the middle to upper Pleistocene of Japan. The newly collected specimens came from two Japanese localities: Numazu, Shizuoka Prefecture (Suruga Bay) and Tosa, Kochi Prefecture (Tosa Bay), included within the known geographical range derived from fossil records. The species identification was based on the close agreement in the cheliped morphology and the known fossil distributions. The new genus is assigned to the subfamily Callichirinae Manning & Felder, 1991, and compared with seven genera, Balsscallichirus Sakai, 2011, Callichirus Stimpson, 1866, Callichiropsis Sakai, 2010, Grynaminna Poore, 2000, Michaelcallianassa Sakai, 2002, Lepidophthalmus Holmes, 1904 and Podocallichirus Sakai, 1999, all characterized by the antennular peduncle being longer and stouter than the antennal peduncle. The new genus is characteristic in combination of the following characters: rostrum spiniform; maxilliped 3 devoid of exopod; ischium-merus of maxilliped 3 broadly operculiform; maxilliped 3 ischium devoid of crista dentata; major cheliped devoid of meral hook or associated lobe-like structure; tergites of the pleomeres 3–5 without conspicuous ornamentation; male pleopod 2 biramous, its endopod devoid of appendices interna and masculina; uropodal endopod suboval in shape; telson distinctly wider than long, with shallowly concave posterior margin. The genetic analysis using the mitochondrial 16S rRNA places the new genus as sister to Callichirus Stimpson, 1866, although bootstrap support for major branches is generally low. The newly collected specimens were found in burrows in soft sediments of shallow subtidal zone being accessible at low tide.

Giant spoon worms pumped out of their deep burrows: First collection of the main bodies of <i>Ikeda taenioides</i> (Annelida: Thalassematidae: Bonelliinae) in 88 years

“…Yabby pumps have been used mainly for the sampling of burrowing crustaceans (e.g., Hailstone & Stephenson 1961, Dworschak 2015, Komai et al 2019). The recent application of this field gear to the collection of echiurans has been very successful as it has made it possible to collect species that have been considered extremely rare (e.g., Ikedosoma elegans) (Komai 2015, Goto et al 2018.…”

A new classification of Callianassidae and related families (Crustacea: Decapoda: Axiidea) derived from a molecular phylogeny with morphological support

“…The type species was described from Japanese Middle Pleistocene fossil chelipeds but extant specimens enabled the species to be described more completely. Komai et al (2019) compared the new genus with several others. Their phylogram based on the 16S rRNA gene found the species closest to Callichirus and more remote from a clade including Neocallichirus, Corallianassa, Glypturus, Glypturoides and Lepidophthalmus.…”