Sternostylus iaspis ( Baba & Haig, 1990 )

Wicksten, Mary K. & Conway, Kevin W., 2023, The Chirostyloidea of the Northeastern Pacific: Host Associations, Range Extensions and a New Species (Decapoda: Anomura, Zootaxa 5284 (1), pp. 167-176 : 173-174

Sternostylus iaspis ( Baba & Haig, 1990) and Sternostylus perarmatus ( Haig, 1968)

( Figs. 5 A, B )

Two other squat lobsters were photographed by ROV during the 2019–2020 cruises off southern California. Both can be distinguished from U. nicoleae sp. nov. by their spinose carapaces.

Sternostylus iaspis ( Baba & Haig, 1990) was photographed while living on the alcyonaceans Paragorgia pacifica Verrill, 1922 and Acanthogorgia sp. at South Osborn Bank (33°21’N 119°2’W), and by the Monterey Bay Aquarium Research Institute at Big Sur Ridge ( Burton et al. 2017). Sternostylus perarmatus ( Haig, 1968) was photographed at Footprint Reef (33° 54’N, 111°51’W, off Anacapa Island). These photographs show it living on the antipatharian Antipathes dendrochristos Opresko, 2005 . As many as eight of these squat lobsters could be seen per host.

Both were well within their recorded ranges: A. iaspis from Vancouver Island to Jasper Seamount, Baja California; and S. perarmatus from north of Anacapa Island, to Coronado Bank, California; and the northern Gulf of California ( Wicksten 2012, Hendrickx et al. 2013).

Hendrickx et al. (2013) gave an extensive account of the habitat, behavior, and abundance of specimens of S. perarmatus (cited as Gastroptychus perarmatus ) in the northern Gulf of California. The squat lobster lived as deep as 710 m, among unidentified sponges and soft corals (probably Callogorgia flabellum ( Ehrenberg, 1834, family Primnoidae ). From 2 to eleven of these squat lobsters lived per colony. One photograph showed a squat lobster removing a large particle from the coral and taking it to its mouth. Video footage showed many large particles of debris in the area. The squat lobster may passively filter particles from the water and at the same time help the coral avoid being coated with debris.

Three additional species of Sternostylus have been collected in eastern Pacific. Sternostylus defensus ( Benedict, 1902) was described from the Galapagos Islands and has been collected at the Partida Seep off Costa Rica, 1052– 1075 m (SIO-BIC C12804). The host was not reported but could have been an antipatharian or alcyonacean (Baba & Wicksten 2020). Sternostylus cavimanus Baba, 1977 has been reported from Peru and Ecuador; and S. milneedwardsi Henderson, 1885 at the extreme southern end of Chile and the Strait of Magellan. The host species of these other two squat lobsters were not recorded.

At present, 13 species of the Chirostyloidea have been reported from the eastern Pacific. The family Chirostylidae includes 5 species of Uroptychus and 2 species of Heteroptychus (Baba and Wicksten 2020) . The family Sternostylidae includes 5 species of Sternostylus . The family Eumunididae is represented by Eumunida subsolanus Baba & Wicksten, 2020 , recently described from off the Galapagos Islands.

Figures

FIGURE 5. A, Sternostylus iaspis on Paragorgia pacifica, San Clemente Escarpment.B, Sternostylus perarmatus on Antipathes dendrochristos, Footprint Reef (34o0’N 119o31’W).