Halobates sexualis, Distant, 1903, Distant, 1903

Samuel, Amos Shem, 2020, Tracing the roots: clarification on the type locality of Halobates sexualis Distant (Heteroptera: Gerridae), Zootaxa 4755 (2), pp. 399-400 : 399

The

marine water strider Halobates sexualis Distant, 1903 was originally described from the estuary of Jambu River ( Distant 1903). This species has been recorded from Malaysia ( Cheng 1985, Zettel & Tran 2009, Ikawa et al. 2012), Sri Lanka ( Andersen & Foster 1992, Ikawa et al. 2012) and Thailand ( Román-Palacios et al. 2018). In the pioneering work by Herring (1961) on this genus, he mentioned the type locality to be “Estuary of the Jambu River, Malaya.” Andersen and Foster (1992) provided notes on the whereabouts of the type locality of this species and mentioned that it was probably located in northern Malaya (Kuala Jambu) immediately south of the border of Thailand on the Gulf of Siam coast. Andersen and Cheng (2004) further backed this up by mentioning Malaysia in the range of H. sexualis , which was not recorded from Malaysia until 2009 ( Zettel & Tran 2009) but also stated that it was not verified personally. However, Distant (1903) mentioned the collection locality as “Estuary of the Jambu River, Jhering.” According to the Map of the Malay Peninsula published around the same time period in 1898 by Stanford, London ( RASGBI 1898), Jambu or Jering is located along the coast of Yaring (formerly Jhering/Jering) which is a District Town in Pattani Province of Thailand. This location is about 120 km northwest of the previously presumed location by Andersen & Foster (1992; see fig. 24) and is most likely the site of collection, which is in present-day Thailand. The type locality of this species should thus be attributed to Thailand instead of Malaysia.

Further, the original description of Halobates sexualis was published in the series “Fasciculi Malayensis: anthropological and zoological results of an expedition to Perak and the Siamese Malay States, 1901–1902 ”, which additionally reinforces the initial basis for this geographic misinterpretation. Some of the past confusion as to whether the type locality lay in Malaysia or not may have arisen because the far southern provinces of Thailand, immediately to the north of the modern Malaysian state of Perak, were for a time referred to by British authorities as the “Siamese Malay States.” This has previously caused some confusion in regard to the type locality for another water strider, Metrocoris nigrofasciatus , which was taken at Bukit Besar, near Nawngchik, which equates to modern Nong Chik, Thailand ( Polhemus 1990, pp. 22–23). This latter locality lies only 23 km to the southwest of the town of Jambu shown in the map accompanying the present manuscript, and as with Jambu, was long interpreted to lie in Malaysia. In both cases, the specimens were collected during the same expedition by Nelson Annandale and Herbert C. Robinson. This former colonial naming convention likely contributed to the confusion as to which Jambu was actually being referred to in the earlier literature.