Phylogeny of the Wormfishes (Teleostei: Gobioidei: Microdesmidae)
Microdesmidae (sensu stricto) includes 30 species of elongate, cryptic, benthic gobioid fishes. The phylogenetic relationships among microdesmid species have been unknown, and the sister taxon to Microdesmidae has been a matter of debate. In this study, the relationships of microdesmid species are hypothesized based on morphological characters, analyzed with cladistic parsimony methods. Characters previously used as evidence for a sister-taxon relationship between Microdesmidae, s.s., and five genera classified as a subfamily (Ptereleotrinae) in an expanded Microdesmidae are reexamined and found to be invalid. Microdesmidae s.s. is restored, including only Cerdale, Clarkichthys, Microdesmus, Gunnellichthys, and Paragunnellichthys. Monophyly of the microdesmid genera is confirmed, and characters diagnosing each genus, and other clades revealed in this analysis, are discussed. The five genera formerly placed in Ptereleotrinae are referred to Ptereleotridae (incertae sedis within Gobioidei), bringing the total number of gobioid families to nine. Microdesmidae is also placed incertae sedis in Gobioidei; some sister-taxon candidates could be excluded based on the characters surveyed in this analysis, but among other gobioids, no clear sister taxon to Microdesmidae could be identified.Abstract
Neurocranium of Microdesmus multiradiatus in (A) dorsal, (B) lateral, and (C) ventral view. Characters referred to in text are indicated; the number corresponds to character number, followed by a number in parentheses indicating the character state. Scale bars = 1 mm
Premaxillae of (A) Gunnellichthys monostigma, (B) Microdesmus multiradiatus, and (C) Cerdale ionthas. Characters referred to in text are indicated; number corresponds to character number, followed by a number in parentheses indicating the character state. Scale bars = 1 mm. Shading in (C) indicates area of thin bone. Gaps in tooth rows in (B) and (C) are the result of damage and are not naturally present
Heads of (A) Gunnellichthys monostigma, (B) Gunnellichthys pleurotaenia, (C) Cerdale ionthas, and (D) Microdesmus multiradiatus. Characters referred to in the text are indicated; number corresponds to character number. Only conditions corresponding to state one for each character are shown. Scale bars = 1 cm
Neurocrania of (A) Cerdale ionthas, (B) Gunnellichthys monostigma, and (C) Sicydium multipunctatum in dorsal view. Characters referred to in text are indicated; number corresponds to character number, followed by a number in parentheses indicating the character state. Scale bars = 1 mm
Suspensoria of (A) Gunnellichthys monostigma, (B) Cerdale ionthas, and (C) Microdesmus carri. Characters referred to in text are indicated; number corresponds to character number, followed by a number in parentheses indicating the character state. Scale bars = 1 mm
Pelvises of (A) Ptereleotris evides and (B) Microdesmus carri. Characters referred to in the text are indicated; number corresponds to character number, followed by a number in parentheses indicating the character state. Shading indicates cartilage. Scale bars = 1 cm
Strict consensus of three cladograms generated by parsimony analysis of 59 morphological characters for 30 microdesmid ingroup and one composite gobioid outgroup taxa. This cladogram has a consistency index of 0.653, retention index of 0.882, and rescaled consistency index of 0.575. Small numbers at each node are Bremer support indices; selected character state changes are indicated on the branches. Reversed characters are indicated with an “R” after the character number, and homoplasious changes by open rather than solid bars
The three alternate most parsimonious reconstructions of relationships within Cerdale. Character state changes are indicated on the branches; reversed characters are indicated with an “R” after the character number. Reconstruction shown in (C) is the same as in strict consensus cladogram shown in Figure 7