Biodiversity Data Journal :
Single Taxon Treatment
|
Corresponding author: Jianjia Wang (wangjianjia@tio.org.cn), Feng Zhang (zhangfeng@hbu.cn)
Academic editor: Bonnie Bain
Received: 07 Jan 2020 | Accepted: 14 Mar 2020 | Published: 17 Mar 2020
© 2020 Jianjia Wang, Dingyong Huang, Wentao Niu, Feng Zhang
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Wang J, Huang D, Niu W, Zhang F (2020) A new species of Cilunculus Loman, 1908 (Arthropoda: Pycnogonida: Ammotheidae) from the South-western Indian Ocean. Biodiversity Data Journal 8: e49935. https://doi.org/10.3897/BDJ.8.e49935
|
|
A new species of Cilunculus was determined by the unique characteristic of the three distal processes present on the almost horizontal proboscis and the other differences, including a shorter and blind ocular tubercle, fewer setae on the legs and a glabrate trunk.
New Cilunculus species from the South-western Indian Ocean
The genus Cilunculus Loman, 1908 consists of 32 species (
Several authors (
Few specimens of Pycnogonida were obtained during the Chinese DY115-20 cruise which undertook the comprehensive survey on the hydrothermal vents along the Southwest Indian Ridge.
The specimens were sorted from benthic fauna which were collected by washing the sediment obtained by a TV-grab from Station DY115-20VII-S04-TVG04 during the Chinese DY115-20 expedition on R/V Dayangyihao in February 2009. They were preserved in 90% ethanol at the Third Institute of Oceanography, Ministry of Natural Resources, China (Nos. 20VIIS4TVG04.01, 20VIIS4TVG04.02). The specimens were drawn using a Camera Lucida and photographs were taken with an Auto-montage system on a Leica M205 FA stereomicroscope. Measurements were made axially, dorsally for the trunk, laterally for the palp, proboscis and leg and are given in millimetres.
Body length 1.79 mm. Trunk glabrous (Fig.
Cilunculus tricuspis sp. n., male; holotype: a. trunk, dorsal view; c. trunk, lateral view; e. proboscis, frontal view; f. palp; g. oviger; h. leg 3; i. tarsus, propodus and claws of leg 3, enlarged. Male; paratype: b. trunk, dorsal view; d. trunk, lateral view. Scale bars a-d = 0.5 mm; e, f, g, i = 0.2 mm; h = 1 mm.
Proboscis barrel-shaped, 0.7 times as long as trunk, with two dorsal and one ventral triangular processes close to mouth.
Chelifores stout, with one-articled scape; chela atrophied, without fingers.
Palp of nine articles (Fig.
Oviger glabrous (Fig.
Third leg (h-i) slender, longest articles with long setae. First coxa short, with few setae; second coxa 1.5 times as long as first or third coxa, with ventrodistal and dorsal protuberances; femur 2.6 times as long as second coxa, with dorsal and distal long setae, tall cement gland tube dorso-distally; first tibia slightly longer than second tibia and 1.4 times longer than femur, with dorsal, lateral and ventral rows of setae; second tibia with ventral and lateral rows of setae and sparse dorsal setae; tarsus small, subtriangular, with one protuberance dorsally, one spine and few setae ventrally; propodus without heel, sole with seven spines and two distal setae, with two long setae dorsally and some short setae dorsally and distally; main claw slender, gently curved, 0.6 times as long as propodus; auxiliary claws half the length of main claw.
Female unknown.
Measurements of holotype in mm: trunk length from the anterior margin of the cephalon to the tip of 4th lateral processes 1.79; width across second lateral processes 1.0; proboscis length 1.27; abdomen length 0.55. Chelifore scape length 0.24. Palp article 1 (Pa1) 0.07; 2 (Pa2) 0.51; Pa3 0.08; Pa4 0.33; Pa5 0.08; Pa6 0.09; Pa7 0.08; Pa8 0.07; Pa9 0.06. Oviger article 1 (O1) 0.11; O2 0.39; O3 0.16; O4 0.35; O5 0.21; O6 0.10; O7 0.08; O8 0.08; O9 0.07; O10 0.02. Third leg: coxa-1 0.26, coxa-2 0.40, coxa-3 0.24, femur 1.06, tibia-1 1.49, tibia-2 1.41, tarsus 0.11, propodus 0.54, main claw 0.32, auxiliary claw 0.16.
This specific name is from the Latin tricuspis (three-pointed), referring to the three processes on the proboscis.
This new species was found only at the type locality, the substrate of which consisted of white and yellow foraminiferan oozing along with dead coral and shells and a small amount of black basalt.
According to the key given by
Cilunculus tricuspis n. sp., keying to couplet 15 of Stock’s key, was distinct from C. cymobostrychos and C. roni in glabrous trunk, without wavy barbed setae or tubercles and distinguished from C. mergus and C. roni by absence of a dorsal hump on the propodus and is also different from C. misesetosus which has long auxiliary claws almost equal to the main claw.
Amongst the 32 species, only Cilunculus australiensis Clark, 1963, Cilunculus galeritus Nakamura & Child, 1991 and C. roni showed the proboscis adorned with processes, but the new species could be easily distinguished from C. australiensis which presented tall spinose tubercles on the trunk and C. galeritus which presented the unique larger cephalic segment hood and could be distinguished from C. roni by the tubercles on the trunk and legs.
There are few species of Cilunculus reported from the Indian Ocean. Amongst these are Cilunculus bifidus (Stock, 1968) only found off False Bay (South Africa) (1361 m) (
This work was supported by the National Youth Science Foundation (Grant No. 41606207), the Scientific Research Foundation of the Third Institute of Oceanography, MNR (Grant No. 2019025) and the China Ocean Mineral Resources Research and Development Association Program (Grant No. DY-125-02-QY-06). Thanks to Dr. Angel De Leon, Dr. Claudia Arango, Dr. Rudá Lucena and Dr. Bonnie Bain for improving this manuscript.