Keijella gonia Zhao & Whatley, 1989

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 : 136-137

Keijella gonia Zhao & Whatley, 1989

Figs. 7A–E , 10

Keijella gonia Zhao & Whatley, 1989: 181 , pl. 3 figs 7–10, 16.

Keijella gonia – Montenegro et al. 2004: pl. 1 fig. 8. — Forel 2021: 8, fig. 5h–i.

Dimensions

L = 0.380 –0.710 millimeters; H = 0.187 –0.380 millimeters; H/L = 0.49–0.62.

Distribution

Modern distribution: Mae Khlong River mouth, north west Gulf of Thailand ( Montenegro et al. 2004); Sedili River, Jason Bay ( Zhao & Whatley 1989); Central Vietnam ( Tan et al. 2021); Indonesia ( Fauzielly 2013); Southwestern coast of Peninsular Thailand, 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 ).

Remarks

Keijella gonia is easily recognized by the distinct angle formed by the posteroventral intersection of vertical and horizontal muri extending into a spine, sometimes sharp and long. The carapace is subrectangular in lateral view, strongly reticulated. Well-preserved specimens show laterally compressed anterior and posterior marginal denticles, especially along AVB. Prominent postero-marginal spines are distinct and located below the marginal denticles especially in juvenile specimens ( Fig. 7A–C ). Figure 10 shows H and L plots of K. gonia compared to the types from Malaysia ( Zhao & Whatley 1989), the specimens from Thailand consist of adults and juveniles.

Figures

Fig. 7. Holocene ostracods from Samut Sakhon Province, Central Thailand. A–E. Keijella gonia Zhao & Whatley, 1989. A. Carapace, left lateral view, SUT-20SS-C310. B. Carapace, left lateral view, SUT-20SS-C311. C. Carapace, left lateral view, SUT-20SS-C312. D. Carapace, right lateral view, SUT- 20SS-C288. E. Carapace, right lateral view, SUT-20SS-C286. – F. Pistocythereis sp. Carapace, right lateral view, SUT-20SS-C305. –G–I. Stigmatocythere bona Chen in Hou, Chen, Yang, Ho, Zhou & Tian, 1982. G. Carapace, right lateral view, SUT-20SS-C201. H. Carapace, left lateral view, SUT-20SS-C200. I. Valve, internal view of right valve, SUT-20SS-C190. – J–O. Keijella multisulcus Whatley & Zhao, 1988. J. Valve, juvenile, right lateral view, SUT-20SS-C231. K. Valve, juvenile, internal view of right valve, SUT-20SS-C213. L. Carapace, male, left lateral view, SUT-20SS-C225. M. Carapace, female, left lateral view, SUT-20SS-C242.N. Carapace, female, left lateral view, SUT-20SS-C206. O. Carapace, female, left lateral view, SUT-20SS-C243. Scale bars = 0.1. mm.

Fig. 10. Height and length scatter plots of Keijella gonia Zhao & Whatley, 1989 from Malaysia (grey circles) compared with specimens found from the whale-fall excavation site in Samut Sakhon Province, north of the Gulf of Thailand (blue circles). Scale bars = 0.1 mm.

Fig. 4. Distribution of Holocene ostracods below and above the whale skeleton level at the whale-fall excavation site in Samut Sakhon Province, north of Gulf of Thailand.