Keijella multisulcus Whatley & Zhao, 1988

Chitnarin, Anisong, Forel, Marie-Béatrice & Tepnarong, Prachya, 2023, Holocene ostracods (Crustacea) from a whale-fall excavation site from the Chao Phraya delta, Central Thailand, European Journal of Taxonomy 856 (1), pp. 120-151 : 136

publication ID	https://doi.org/ 10.5852/ejt.2023.856.2033
publication LSID	lsid:zoobank.org:pub:A519A06A-6C20-45A7-9120-B0C795E41E75
DOI	https://doi.org/10.5281/zenodo.7616282
persistent identifier	https://treatment.plazi.org/id/1710512C-FFF1-FF92-DF46-FE65FA885150
treatment provided by	Felipe
scientific name	Keijella multisulcus Whatley & Zhao, 1988
status

Treatment

Keijella multisulcus Whatley & Zhao, 1988 View in CoL

Figs 7J–O View Fig , 8A–I View Fig , 9 View Fig

Keijella multisulcus Whatley & Zao, 1988: 15 View in CoL , fig. d.

Dimensions

L = 0.325 –0.875 millimeters; H = 0.175 –0.444 millimeters; H/L = 0.45–0.59 ( Fig. 9 View Fig ).

Distribution

Modern distribution: Malacca Strait ( Whatley & Zhao 1988b); Malaysia ( Omar et al. 2017); Mae Khlong River mouth, north west Gulf of Thailand ( Montenegro et al. 2004); southwestern coast of Peninsular Thaiand, Ao Nun, Satun Province, Andaman Sea ( Forel 2021).

Fossil distribution: Bangkok Clay (samples 20SS01B, 02A, 02B, 03A, 04A, 04B), whale excavation site, Samut Sakhon Province, Thailand, Late Holocene (this work, Fig. 4 View Fig ).

Remark

Dimorphism of Keijella multisulcus can be recognized by the subrectangular shape with H/L ratio less than 0.50 in the male ( Fig. 7L View Fig ) and the subovate shape with a higher H/L ratio in the female ( Fig. 7M–O View Fig ). The juvenile carapaces are sub-triangular in lateral view with Hmax located anteriorly at one third of L, Lmax is located below midH in both valves. The ventral longitudinal carina is prominent in young juveniles ( Fig. 8G–H View Fig ) and extends into a small spine (posteroventral spine). The ventral longitudinal carina is faint and becomes obscured in the larger juvenile stage ( Fig. 8A–F View Fig ). Small conical posterior marginal denticles and a large terminal posteroventral spine are observed in juveniles. Figure 9 View Fig shows H and L plot of the species which clearly demonstrates that sexual dimorphism can be differentiated in adult specimens.