First record of the genus Boholina (Copepoda, Calanoida, Pseudocyclopidae) in Vietnam, with description of a new species from an anchialine cave in Tra Ban Island.

Duc Luong Tran,Cheon Young Chang

doi:10.3897/zookeys.977.55040

Abstract

A new species, Boholina reductasp. nov., was found in a brackish pool within an anchialine cave in Tra Ban Island in Bai Tu Long Bay, north Vietnam. The new species is clearly distinguished from all the six species currently known in the genus Boholina by the following unique characteristics: reduction of the septum between gonopores; narrow and pointed rostrum; basal segment of mandibular palp armed with three setae; maxillule without seta on the basal exite, and exopod with 11 setae; second and third endopodal segments of the maxilliped bearing three setae each; exopod of male right leg 5 2-segmented, with two strong and one vestigial spines on the outer margin of the distal segment; and last exopodal segment of female leg 5 bearing only one spine on the outer margin. We provide a description of the new species, along with detailed illustrations and scanning electron microscopy photographs. The identification key to Boholina species is updated as well. This is the first record of the genus Boholina from Vietnam.

Highlights

The family Boholinidae was established for a single genus Boholina by Fosshagen and Iliffe (1989) on the basis of a combination of morphological characteristics: well-developed mouthparts; 3-segmented rami on P1–P4; female P5 with 3-segmented exopod and slightly reduced 2-segmented endopod; right antennule of male geniculated; and male P5 with a highly complex grasping organ
14 genera have been recognized in Pseudocyclopidae as follows: Badijella Kršinic, 2005; Boholina Fosshagen, 1989; Brattstromia Fosshagen, 1991; Exumella Fosshagen, 1970; Exumellina Fosshagen, 1998; Hondurella Suárez-Morales & Iliffe, 2007; Normancavia Fosshagen & Iliffe, 2003; Pinkertonius Bradford-Grieve, Boxshall & Blanco-Bercial, 2014; Placocalanus Fosshagen, 1970; Pseudocyclops Brady, 1872; Ridgewayia Thompson & Scott, 1903; Robpalmeria Fosshagen & Iliffe, 2003; Stargatia Fosshagen & Iliffe, 2003 and Stygoridgewayia Tang, Barron & Goater, 2008 (Walter and Boxshall 2020)
Other genera are known from the North Atlantic and Mediterranean (Exumella, Badijella), Belize (Brattstromia), Bahamas (Exumellina, Normancavia, Robpalmeria, Stargatia), Western Caribbean (Hondurella), Australia and New Zealand (Stygoridgewayia, Pinkertonius)

Summary

Introduction

The family Boholinidae was established for a single genus Boholina by Fosshagen and Iliffe (1989) on the basis of a combination of morphological characteristics: well-developed mouthparts; 3-segmented rami on P1–P4; female P5 with 3-segmented exopod and slightly reduced 2-segmented endopod; right antennule of male geniculated; and male P5 with a highly complex grasping organ. Fosshagen and Iliffe (1989) argued that it differed from the families Pseudocyclopidae Giesbrecht, 1893 and Ridgewayiidae Wilson, 1958 by the modified terminal spine on the distal exopodal segment of P4 and the inner seta on the coxal segment of female P5 (Fosshagen and Iliffe 1989). 14 genera have been recognized in Pseudocyclopidae as follows: Badijella Kršinic, 2005; Boholina Fosshagen, 1989; Brattstromia Fosshagen, 1991; Exumella Fosshagen, 1970; Exumellina Fosshagen, 1998; Hondurella Suárez-Morales & Iliffe, 2007; Normancavia Fosshagen & Iliffe, 2003; Pinkertonius Bradford-Grieve, Boxshall & Blanco-Bercial, 2014; Placocalanus Fosshagen, 1970; Pseudocyclops Brady, 1872; Ridgewayia Thompson & Scott, 1903; Robpalmeria Fosshagen & Iliffe, 2003; Stargatia Fosshagen & Iliffe, 2003 and Stygoridgewayia Tang, Barron & Goater, 2008 (Walter and Boxshall 2020) Among these genera, Pseudocyclops and Ridgewayia have a worldwide distribution from temperate, subtropical to tropical shallow waters (Ohtsuka et al 1999; Boxshall and Halsey 2004; Figueroa 2011a, b).

Materials and methods

Absent 2 sigmoid spines