Morphological and molecular characterisation of digenean parasites of the Galápagos sheephead Semicossyphus darwini (Jenyns) with the re-description of Labrifer secundus Manter, 1940 (Lepidapedidae) from the Humboldt Current Large Marine Ecosystem

Abstract

The Humboldt Current Large Marine Ecosystem (HCLME) is recognised as one of the largest and most productive marine ecosystems. The estimated number of teleost fish species for the Chilean coast influenced by the HCLME reaches c.1,030 but digeneans have been reported for 39 teleost species, i.e. less than 4% of the potential hosts. During a survey of parasites of the Galápagos sheephead wrasse Semicossyphus darwini (Jennyns) (Perciformes: Labridae) from off northern Chile, we obtained representatives of three digenean species, Helicometrina nimia Linton, 1910 (Opecoelidae), Proctoeces humboldti George-Nascimento & Quiroga, 1983 (Fellodistomidae) and Labrifer secundus Manter, 1940 (Lepidapedidae). Labrifer secundus, originally described from Semicossyphus pulcher (Ayres, 1854) off the coast of Baja California, Mexico is re-described. Helicometrina nimia is a common parasite from littoral fishes in the HCLME. Semicossyphus darwini is a new host for these three digenean species.

Missing link: California rock crabs serve as intermediate hosts for the parasite Helicometrina nimia

“…The 18S sequence from metacercariae retrieved from C. productus returned a closest match with H. nimia , with 98.93% (KJ995999, ex Acanthistius pictus , brick sea bass, Chile; see Gonzalez, 2016). The 18 s sequence from R. antennarium also returned a closest match with H. nimia , with 98.64% (KY614306, ex Semicossyphus darwini , Galapagos sheephead wrasse, Chile; see Ñacari et al ., 2018). In three partial 18 s sequences (two ex C. productus and one ex R. antennarium ) with coverage at 307 bp, there were four haplotypes shared by the metacercarial sequences that were different from three exemplar sequences from South America (KJ995995, González et al, 2013; KY614306, Ñacari et al ., 2018; KF938641, Oliva et al, 2015).…”

“…The 18 s sequence from R. antennarium also returned a closest match with H. nimia , with 98.64% (KY614306, ex Semicossyphus darwini , Galapagos sheephead wrasse, Chile; see Ñacari et al ., 2018). In three partial 18 s sequences (two ex C. productus and one ex R. antennarium ) with coverage at 307 bp, there were four haplotypes shared by the metacercarial sequences that were different from three exemplar sequences from South America (KJ995995, González et al, 2013; KY614306, Ñacari et al ., 2018; KF938641, Oliva et al, 2015). Previous reporting of 18 specimens of H. nimia from three different host species found nine variable sites in the 18 s region from a partial sequence of 372 bp, with an average pairwise difference of three (Oliva et al , 2015).…”