Tuesday, October 18, 2022

[Crustacea • 2022] Siambathynella janineana • A New Species of the Genus Siambathynella (Bathynellacea: Parabathynellidae) from A Thai Cave

Siambathynella janineana
Camacho & Leclerc, 2022

Siambathynella janineana sp. nov. (family Parabathynellidae) discovered in Thailand is herein described. The new species displays an exclusive character: a distinctive organ on the antennule of males. It also displays a unique combination of morphological characters, including a seven-segmented antennule and antenna, sexual dimorphism of the antennule, a one-segmented exopod on thoracopod I and a two-segmented one on thoracopods II to VII, a male thoracopod VIII without basipodial setae and with a trapezoidal outer lobe, a female thoracopod VIII with two denticles at the base of two setae, pleopods absent, a sympod of the uropod with an inhomonomous row of spines and an uropod endopod with a spinous distal process and a very large distal spine covered with setules.

This is the fifth record of Bathynellacea (family Parabathynellidae) found in caves in Thailand.

Keywords: cave, groundwater, Parabathynellidae, Siambathynella, Thailand

Order Bathynellacea Chappuis, 1915


Genus Siambathynella Camacho, Watiroyram & Brancelj, 2011

Type species: Siambathynella laorsriae Camacho, Watiroyram & Brancelj, 2011.
Siambathynella janineana sp. nov. Habitus male.

 Siambathynella janineana sp. nov.
Ecology: The material of Siambathynella janineana sp. nov. studied was collected from a pool located in the upper gallery of Tham Chiang Dao Cave. In addition to these specimens, numerous others were sampled by Janine Gibert either by filtering another pool in the upper gallery using a plankton net with an 0.150 mm mesh [about 305 specimens (sp.) were collected with this method] or by using artificial substrates in the same pool (215 sp.) (Gibert 1987). A few specimens were also found in the terminal sump of the tourist gallery (1 sp.), at the outside emergence (1 sp.) and in a Bou-Rouch pump that was positioned about 25 m downstream of the emergence (40 cm depth and 20 l filtered) (1 sp.). The most abundant populations found in the cave were Bathynellacea, with a total of 523 specimens (Gibert 1987). Other taxa collected included mainly ostracods, a few cyclopoid copepods and rarely gastropods and harpacticoid copepods (Gibert 1987). The temperature of the sampled waters varied between 21 °C and 23 °C during July 1985.

Etymology: The species name “janineana” (adjective) is dedicated to Prof. Janine Gibert, who passed away in 2009. She was head of the Groundwater Hydrobiology and Ecology Laboratory (UMR CNRS 5023, Laboratoire d’Ecologie des Hydrosystèmes Fluviaux, Hydrobiologie et Ecologie Souterraines) at Université Claude Bernard Lyon 1 in France. She worked in various international programs on subterranean biodiversity and groundwater ecology from the perspective of environmental sustainability, particularly in the project “Protocols for the ASsessment and Conservation of Aquatic Life In the Subsurface (PASCALIS)”. She was also a member of the biospeleological team that led Expedition Thai-Maros in 1985 and was highly active in the sampling of the caves, especially Tham Chiang Dao.

Ana I. Camacho and Philippe Leclerc. 2022. A New Species of the Genus Siambathynella Camacho, Watiroyram & Brancelj, 2011 (Crustacea, Bathynellacea, Parabathynellidae) from A Thai Cave. Subterranean Biology. 44: 139-152. DOI: 10.3897/subtbiol.44.93661