Jassa orientalis ( Dana, 1852a )

Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, Zootaxa 4939 (1), pp. 1-191 : 161

Jassa orientalis ( Dana, 1852a)

Dana (1852a) originally named this species Gammarus orientalis , changing it to Cratophium orientale the following year ( Dana 1853). Dana (1853) based his description of this species on a single specimen captured “From the sea, off the eastern entrance of the Straits of Sunda. Collected, March 4, 1842.” This was during the United States Exploring Expedition led by Charles Wilkes (1838–1842). Bate (1862) transferred it to the genus Podocerus . Della Valle (1893) synonymized it with P. falcatus (now Jassa falcata ). As noted in Conlan (1990), the type specimens were lost (confirmed absent from the collection of the Smithsonian Institution, National Museum of Natural History, 13 May 2019 by Karen Reed, Museum Specialist, Department of Invertebrate Zoology). Dana’s (1853) Plate 56, Fig. 3 , showing the whole body and gnathopod 2 of a female or non-thumbed male, indicate that the specimen is indeed a Jassa , but the species cannot be determined from the description and illustration.

Since Jassa as a genus is not known from Indonesia, it is possible that this specimen was a species of Jassa that had been displaced from one of Wilkes’ six ships, all of which may have been fouled by Jassa , as occurred in the Challenger Expedition (see Results: Distribution). The ships used by the Wilkes expedition departed from Hampton Roads, Virginia in 1838 ( Philbrick 2004). Jassa marmorata has been known from this coast since 1883 (Table 3) and currently it is the only species of Jassa known from the Virginia coast ( Figs 1–2 ), suggesting that the ships were fouled by this species and subsequently dispersed to temperate coasts of South America, Australia and the Pacific U.S. that were visited by the Wilkes expedition. Therefore, it is possible that Cratophium orientale is synonymous with Jassa marmorata but the loss of the type specimens cannot make this unequivocal.

Figures

FIGURE 1. Progressive discovery of Jassa marmorata from 1850 to 1949. Red dot: identification confirmed by specimen examination; green triangle: literature record (Supplementary Table S1) with identification not confirmed but judged likely to be this species; blue x: suspected or known to be on the hull or interior of a boat or ship.

FIGURE 2. Progressive discovery of Jassa marmorata from 1850 to 2020. Red dot: identification confirmed by specimen examination; green triangle: literature record (Supplementary Table S1) with identification not confirmed but judged likely to be this species; blue x: suspected or known to be on the hull or interior of a boat or ship.

FIGURE 3. Progressive discovery of Jassa slatteryi from 1850 to 1949. Red dot: identification confirmed by specimen examination; green triangle: literature record (Supplementary Table S1) with identification not confirmed but judged likely to be this species; blue x: suspected or known to be on the hull or interior of a boat or ship.