Gobiodon histrio (Valenciennes, 1837)

Gobiodon histrio (Valenciennes, 1837) View in CoL : Broad-barred Coralgoby

Synonyms or described as: Gobius histrio (Valenciennes, 1837) and Gobiodon verticalis ( Alleyne and Macleay, 1877) .

Description: Gobiodon histrio was once considered a single species in conjunction with G. erythrospilus . Gobiodon erythrospilus was listed as a subspecies in a prior guide by Munday et al. (1999), who referred to an “erythrospilus form” of G. histrio . However, it has since been confirmed that the ‘erythrospilus’ form is a distinct species and no longer belongs to this species ( Shibukawa, Suzuki and Aizawa, 2013). Despite obvious similarities in colouration, there are several ways that G. histrio differs from G. erythrospilus . Most notable of these is the pattern of the red markings on a lime green/teal body, which are not defined spots or loose highly broken lines as seen in G. erythrospilus . Instead, G. histrio have irregular horizontal lines that are occasionally broken in sections or connected to other parallel lines, or a combination of open and closed bands that may or may not form a consistent line. There are four to five broad red bands vertically down the facial region, with a visible black spot on the upper base of the opercular margin. Fin colouration is described as pale green or light brown, and a red horizontal line can sometimes be observed on the lower portion of the dorsal fin ( Figure 16 View FIGURE 16 ).

Distribution: As stated for G. erythrospilus , the relative abundance of the two species changes with latitude, with G. histrio occurring in higher abundance in the northern latitudes at locations such as Kimbe Bay, Papua New Guinea (see G. erythrospilus for more information) ( Munday, Harold and Winterbottom, 1999). Gobiodon histrio can be observed throughout the Indo-Pacific with the population spanning throughout the Red Sea, South East Asia, Japan, both Australian coasts and the South Pacific Islands (GBIF.Org, 2024).

Habitat: The species is commonly observed in the corymbose and caespitose corals A. nasuta , A. valida , A. cerealis , A. secale , A. loripes , A. millepora and A. tenuis ( Munday, Harold and Winterbottom, 1999; Froehlich et al., 2023).

Status: Gobiodon histrio is listed as being of ‘Least Concern’ on the IUCN Red List ( Acero et al., 2010).

Sociality: Gobiodon histrio is most frequently observed occupying corals in pairs but can be found in small groups (mean group size: 1.71, SI: 0.33–0.43) ( Hing et al., 2018; Hing, 2019; Froehlich et al., 2024).

Genetics: Genetic analyses consistently display a strong phylogenetic relationship with G. erythrospilus as suggested by the similarity in appearance ( Harold et al., 2008; Duchene et al., 2013; Herler, Bogorodsky and Suzuki, 2013; Hing et al., 2019). Gobiodon histrio was placed in a clade with G. erythrospilus , G. fuscoruber , G. axillaris and G. ater ( Harold et al., 2008; Duchene et al., 2013; Herler, Bogorodsky and Suzuki, 2013; Hing et al., 2019).