Thursday, February 28, 2019

[Hexapoda • 2019] Coecobrya sirindhornae • the Most Highly Troglomorphic Collembola (Entomobryidae) in Southeast Asia


Coecobrya sirindhornae
Jantarit, Satasook & Deharveng, 2019


Abstract
The most highly troglomorphic Collembola of Southeast Asia, Coecobrya sirindhornae sp. n., is described from a cave in Satun province, Thai Peninsula. It is characterised by its large size, extremely elongated antennae, relatively long legs and furca, reduced macrochaetotaxy, very long and slender claw, pointed tenent hair, four sublobal hairs on outer maxillary lobe, and the absence of eyes and pigmentation. A checklist of Thai Coecobrya species and a key to the troglomorphic species of Thailand are provided. Troglomorphy and conservation of cave habitats in the area are discussed.

Keywords: new species, peninsular Thailand, subterranean environment, taxonomy, troglomorphy

Figure 1. Coecobrya sirindhornae sp. n. A–D Habitus

E–F Two morphological types of cave Coecobrya in Thailand E Coecobrya phanthuratensis Zhang & Jantarit, 2018; normal form with short antennae, appendages and small size F Coecobrya polychaeta Zhang & Nilsai, 2017; troglomorphic form with long antennae and appendages with large body size
and G Coecobrya sirindhornae sp. n., highly troglomorphic characters with extremely long antennae and appendages and also large body size.


Coecobrya sirindhornae sp. n.
 
A–B Habitus, C. sirindhornae sp. n., highly troglomorphic characters with extremely long antennae and appendages and also large body size. 

E–F Two morphological types of cave Coecobrya in Thailand 
Coecobrya phanthuratensis Zhang & Jantarit, 2018; normal form with short antennae, appendages and small size F Coecobrya polychaeta Zhang & Nilsai, 2017; troglomorphic form with long antennae and appendages with large body size 
and G Coecobrya sirindhornae sp. n., highly troglomorphic characters with extremely long antennae and appendages and also large body size.

Taxonomy
Class Collembola Lubbock, 1873
Order Entomobryomorpha Börner, 1913

Family Entomobryidae Tömösváry, 1882
Subfamily Entomobryinae Schäffer, 1896

Genus Coecobrya Yosii, 1956
Coecobrya sirindhornae sp. n.


Figure 2. Coecobrya sirindhornae sp. n. continued.
A Distal part of Ant. II dorsally of left antenna B Ant. III organ of left side C Distal part of Ant. IV with subapical organite D Ratio of antennal length E Clypeal chaetae F Prelabral and labral chaetae G Labial palp H Outer maxillary lobe I Mandibles J Ventro-distal complex of labrum K Chaetae of labial basis and ventral chaetotaxy of head.

Figure 7. Distribution of three troglomorphic Coecobrya species in Satun caves, all located in lowland areas.

Ecology: Coecobrya sirindhornae sp. n. is restricted to the dark zone of the cave where it has been found, in the oligotrophic environment of a small chamber, on muddy ground and wet rock walls. The chamber is connected to a narrow steep hole. Small puddles are present in the chamber and water is dripping from the ceiling. Muddy ground surface is flooded during rainy season. Some individuals were found feeding on a cricket corpse. They were quick jumping and moved rapidly. The species is found only in that chamber where humidity is at saturation, and temperature is constant (23‒24 degrees Celsius). The population seems rather limited (only 26 specimens were collected from five attempts, each time one hour collecting by 2 people). Small (young) individuals were less numerous and not collected.

Etymology: This species is named to honour Her Royal Highness Princess Maha Chakri Sirindhorn, who is passionately interested in natural history and plays an important role in promoting the conservation of biodiversity and the environment of Thailand.


 Sopark Jantarit, Chutamas Satasook and Louis Deharveng. 2019. Coecobrya sirindhornae sp. n., the Most Highly Troglomorphic Collembola in Southeast Asia (Collembola, Entomobryidae). ZooKeys 824: 21-44.  DOI: 10.3897/zookeys.824.31635