Dismantling the Trachinoidei: evidence of a scorpaenoid relationship for the Champsodontidae Randall D. Mooi 1 & G. David Johnson2 JVertebrate Zoology, Milwaukee Public Museum, 800 West Wells St., Milwaukee, WL 53233-1478 USA (e-mail: [email protected]) 2Division of Fishes, National Museum of Natural History Smithsonian Institution, Washington, D.C., 20560 USA (Received 17 September 1996; in revised form 30 Januao, 1997; accepted 31 Janua~ 1997) Mooi, R. D. and G. D. Johnson. 1997. Dismantling the Trachinoidei: evidence of Ichthyological a scorpaenoid relationship for the Champsodontidae. Ichthyol. Res., 44 (2): Research 143-176. :O, The Ichthyological Society of Japan 1997 Abstract An examination of the osteology and myology of the Champ- sodontidae reveals a number of apomorphic features (e.g., double-headed pala- tine, large pelvic radial, epaxial muscle inserting on the medial pelvic-fin ray, posterior levator internus inserting on the third epibranchial). The evidence for a Champsodontidae/Chiasmodontidae relationship is examined through a re-evalu- ation of the basal characters used to define the suborder Trachinoidei. The Champsodoutidae are removed from the Trachinoidei and a chiasmodontid sister relationship is rejected. After investigation of severaI possible alternative rela- tionships (Paracanthopterygii, Gobioidei, Callionymoidei, Kurtoidei, Apogo- nidae, Blennioidei, Trichodontidae), champsodontids are hypothesized to be members of the perciform suborder Scorpaenoidei. This hypothesis is based largely on the synapomorphy of a parietal spine with an opening for passage of the supratemporal sensory canal, a unique condition of champsodontids and some scorpaenoids. A shared Type 1 epaxial muscle morphology, with separate fibre insertions on the distal tips of the spine-bearing dorsal-fin pterygiophores, is unusual and probably derived among perciforms. Champsodontids also share with some scorpaenoids Type 5 spinoid scales and the origin of Baudelot's liga- ment from the first vertebra rather than the basi-occipital, although neither of these features is unique to these taxa. The occurrence of an enclosed sensory. canal on the parietals of Trichodontidae suggest that their relationships might also lie with the Scorpaenoidei. Arguments pertaining to the removal of champ- sodontids from the trachinoids apply equally to the hypothesized membership of the Cheimarrichthyidae, Pinguipedidae, Percophididae, Trichonotidae, Creedi- idae, Chiasmodontidae, and notothenioids in the Trachinoidei. Inclusion of these taxa within the Trachinoidei is not well-supported, and their relationships require further investigation. Key words. -- Champsodontidae; phylogeny; Scorpaenoidei; Trachinoidei. he Champsodontidae, commonly known as are characterized by a large head and mouth, T gapers, are a family of small, elongate small pectoral fins, very large pelvic fins, un- fishes found at depths between 50-400m usual pedicellate spinoid scales, and series of throughout the tropical Indo-Pacific. They are sensory papillae on the head and body (Fig. la). currently considered to be members of the large Early authors had difficulty aligning the genus order Perciformes. A recent taxonomic review among other groups due to its unusual morphol- recognized one genus, Champsodon, with 13 ogy. Traditionally, it has been placed in the sub- species (Nemeth, 1994). Externally, the adults order Trachinoidei, a taxon that has had a fluid 144 R.D. Mooi & G. D. Johnson Fig. 1. General body forms of the Champsodontidae and Chiasmodontidae. a) Champsodon capensis (after Smith and Heemstra, 1986: fig. 229.1); b) Pseudoscopelus scriptus (after Norman, 1929: fig. l l). membership. Among the trachinoids, Champ- a number of unique features that corroborate sodon has been most frequently allied with the monophyly, as well as some unusual characteris- Chiasmodontidae (swallowers) to which it bears tics that are found in only a few acanthomorph a superficial resemblance (Fig. 1), but opinions taxa. These apomorphies may prove to be vary among authors and little, if any, evidence synapomorphies of Champsodon and other has been provided to support these opinions. groups upon further study. We re-examine and Pietsch (1989) and Pietsch and Zabetian discount the current hypothesized affiliation with (1990) provided a cladistic definition of a Tra- trachinoids, and comment on the composition of chinoidei that included the Champsodontidae the Trachinoidei based on reinterpretation of evi- and Chiasmodontidae as sister taxa. Reserva- dence and removal of the Champsodontidae. We tions concerning their evidence and conclusions then explore alternative relationships for champ- were voiced by Johnson (1993) and Mooi and sodontids with special emphasis on their ties to Gill (1995), who suggested alternative relation- the scorpaenoids. ships including placement among the Scor- paenoidei (sensu Mooi and Gill, 1995). These same reservations cast some doubt on the in- Methods tegrity of the Trachinoidei as a whole. The contentious phylogenetic position of the Osteological observations were made from Champsodontidae and its possible implications specimens cleared and stained by various tech- for higher relationships provided the impetus for niques (Tayloc 1967; Dingerkus and Uhler, the current study. After a brief taxonomic his- 1977; Taylor and Van Dyke, 1985). Additional tory, we present a detailed description of the os- comparative information was derived from the teology and myology of Champsodon, revealing literature, particularly Johnson and Cohen A Scorpaenoid Relationship for Champsodontidae 145 (1974) for chiasmodontids, Nemeth (1994) re- cleared and stained (CS) specimens are indicated; speci- garding champsodontids, and Pietsch (1989) for mens not so designated were examined externally only. For trachinoids. Champsodon, alphabetically by species and institution: C. atridorsalis, USNM 297752 (D), USNM 323056 (D,CS); Vertebral counts are divided into abdominal C. capensis, USNM 270267 (CS), USNM 307516 (D); C. and caudal, the first caudal defined as the anteri- fimbriatus, USNM 51682 (D); C. guentheri, USNM 150759 ormost vertebra with a haemal spine. Intermus- (CS); C. longipinnis, MCZ 60955 (CS), USNM 149650 cular bones are identified as epineurals rather (D), USNM 150948 (D); C. nudivittatus, USNM 122582 than epipteurals following Johnson and Patterson (D,CS), USNM 297753 (D); C. omanensis, USNM 305988 (D); C. sagittus, USNM 122405 (D); C. seychellensis, (1993) and Patterson and Johnson (1995). The USNM 307487 (D); C. snyderi, MCZ 99264 (CS), USNM pattern of insertion of dorsal- and anal-fin ptery- 149294 (D); C. vorax, USNM 122400 (CS), USNM 168220 giophores within interneural and interhaemal (D), USNM 245331 (D, CS), USNM 297751 (D); C. sp. spaces are provided as "fin formulae" modified (unidentifiable larval material), AMS 1.20948-002, AMS from the "anterior fin pterygiophore formulae" 1.22548-003, AMS t.24553-009, AMS 1.24570-013 (CS), of Gill and Randall (1994). Neural and haemal AMS 1.24898-001, AMS 1.24949-003, AMS 1.24953-009, AMS 1.24955-00l, AMS 1.24967-009, AMS 1.26192-002 spines are represented by slashes, pterygio- (CS), AMS UN.91113-006 (CS), AMS UN.91113-007 phores are represented by roman numerals when (CS), MCZ 68883 (CS), USNM 245330 (CS), USNM bearing spines ("II" indicating a pterygiophore 245331 (CS), ZMC 1368V-Vt, ZMC 3724I,VI (CS). bearing a supernumerary and serially associated Comparative material, alphabetically by family and in- spine, 'T' a pterygiophore bearing only a serially stitution. -- Ammodytidae: Ammodytes dubius, USNM 302247 (CS). Anoplopomatidae: Anoplopoma fimbria, associated spine) and arabic numerals when USNM 269910 (CS). Antennariidae: Antennarius radiosus, bearing serially associated segmented rays. USNM 266728 (CS): Histrio histrio, USNM 269469 (CS). Spineless pterygiophores are indicated by a "P" Bathydraconidae: Parachaenichthys georgianus, USNM and pterygiophores in the same interneural space 301814 (CS). Batrachoididae: Batrachoides liberiensis, are separated by "+." Terminology for caudal USNM 219393 (CS); Daector dowi, MPM 31153 (CS); cartilages follows Fujita (1989). Opsanus tau, USNM 104906 (CS); O. beta, MPM uncat. (CS); O. sp., MPM 242; Porichthvs porosissimus, USNM Cheek musculature was examined in ethanol- 270371 (CS). Bovichtidae: Bovichtus variegatus, USNM preserved specimens by removing the eye, sub- 2 t4761 (CS). Caltionymidae: Synchiropus ocellatus, orbitals, and skin on one side of the head. Mus- USNM 270215 (CS). Caracanthidae: Caracanthus macula- cle bundles were identified, drawn under a ms, USNM 214027 (CS). Channichthyidae: Champ- binocular dissecting microscope through a cam- socephahts gunnari, USNM 305271 (CS). Cheimarrichthyi- dae: Cheimarrichthysfosteri, USNM 198509 (CS), USNM era lucida, then removed to reveal more medial 214023 (CS). Chiasmodontidae: Chiasmodontidae sp., muscle groups. Branchial, pelvic, and pectoral AMS 1.16492-034, AMS 1.16725-015, AMS 1.24508-002, musculature was examined both in situ and after AMS 1.24511-002, AMS 1.24514-001, AMS 1.24528-002, removing the elements from the fish. Epaxial AMS 1.24866-001, AMS 1.24948-002, AMS 1.24957-002, muscle examination follows the methods of AMS 1.24971-001, AMS 1.25199-001, AMS 1.25556-006; Mooi and Gill (t995). Muscle delineation was Chiasmodon niger, ARC 8600869, ARC 8600887 (CS); C. sp., MCZ 65529, USNM 254264 (CS), USNM 331703 enhanced by staining with a variation on Lugol's (CS); Dysalotus alcocki, MCZ 60722, MCZ 60760, MCZ solution