Lambeia pectinatus, Mickle, 2017

Mickle, Kathryn E., 2017, The lower actinopterygian fauna from the Lower Carboniferous Albert shale formation of New Brunswick, Canada - a review of previously described taxa and a description of a new genus and species, Fossil Record 20 (1), pp. 47-67 : 55-57

Lambeia pectinatus n. gen. n. sp. ( Figs. 4–10 )

Etymology: pectinatus in reference to the pectinations on the dorsal ridge scales and ventral and posterior margins of the scales.

Diagnosis (based on the unique combination of characters): large edentulous tuberculated ventral rostro-premaxilla; median dorsal rostral bone; maxilla with broad postorbital plate; complex ganoine ornamentation on maxilla; nasal bones with ganoine ornamentation of tubercles and short ridges ventrally, longer diagonally oriented ridges mid-bone; single rectangular-shaped supraorbital bone; numerous suborbital bones; dermopterotic as long as the parietal plus the post-parietal bones; presupracleithrum; dermohyal; series of accessory opercular bones; 12 branchiostegal rays; two lateral gular plates; six dorsal ridge scales beginning at scale row 20; first three dorsal ridge scales with pectinated posterior margins; dorsal ridge scales occupy the space of two body scale rows; body scales rows intermittently inserted between adjacent dorsal ridge scales; anal fin almost opposite dorsal fin; dorsal and anal fins posteriorly placed on the body; body depth dramatically decreases posterior to dorsal fin; large pectoral and pelvic fins; body scales with pectinated posterior margins and horizontal ganoine ridges; ventrally placed scales from scale row 5 to the end of pelvic fin have pectinated posterior and ventral margins.

Holotype and only specimen: YPM 8664 ( Figs. 4–10 ). The holotype YPM 8664 preserves the anterior two-thirds of a rather large fish in lateral view ( Fig. 4 ). The counterpart is missing. The caudal peduncle and fin are not preserved. Though the distal portion of the dorsal fin is missing, the proximal portion along the body is preserved and appears to be complete. The pectoral, pelvic, and anal fins are large and spectacularly preserved ( Fig. 4 ). Though the specimen is not complete, it is a medium- to large-sized palaeoniscoid with a length of 19.5 cm, minus the caudal peduncle and fin. It is noted that this fish is preserved on a slab with the remains of three other smaller palaeoniscoids.

Type locality: Tournaisian (Lower Carboniferous) Albert Formation, New Brunswick, Canada.

Figures

Figure 4. Type and only specimen of †Lambeia pectinatus. (a) Photograph of the latex peel of YPM 8664; (b) illustration based on YPM 8664. Dashed lines represent areas of ambiguity that have been reconstructed. Long dark gray dashed line represents lateral-line-bearing scales. Scale bars equal 5 mm.

Figure 5. Photographs of the lateral view of the head of the latex peel of type specimen of †Lambeia pectinatus, YPM 8664. Scale bars equal 5mm.

Figure 6. Reconstruction of the head of †Lambeia pectinatus detailing bones and ganoine ornamentation. Illustration based on type and only specimen, YPM 8664. Abbreviations: ao, antorbital; aop, accessory opercular bones; br, branchiostegal rays; cl, cleithrum; d, dentary; dh, dermohyal; dpt, dermopterotic; dsp, dermosphenotic; ex, extrascapular; io, infraorbital; lg, lateral gular; mdr, median dorsal rostral; mg, median gular; mx, maxilla; n, nasal; op, operculum; p, parietal; pc, postcleithrum; pop, preoperculum; pp, post-parietal; ps, presupracleithrum; pt, posttemporal; sc, sclerotic; scl, supracleithrum; so, suborbital; sop, suboperculum; sup, supraorbital; vr-pmx; ventral rostro-premaxilla. Dark gray filled circles represent sensory pores; light gray areas represent areas of infilling; dashed lines represent areas of ambiguity and reconstruction.

Figure 7. Dorsal ridge scales of †Lambeia pectinatus. (a) Photograph of dorsal ridge scales in type and only specimen (YPM 8664). (b) Illustration of dorsal ridge scales in YPM 8664. Abbreviations: bsi, inserted body scales; df, dorsal fin; drs, dorsal ridge scales. Scale bars equal 5 mm.

Figure 8. Schematic drawing detailing the scale regions described in the text for †Lambeia pectinatus (YPM 8664). A1, A2, A3: dorsal-most, mid-body, and ventral-most scales posterior to the pectoral girdle; B1, B2, B3: dorsal-most, mid-body, and ventral-most scales from scale rows 6–12; C1, C2, C3: dorsal-most, mid-body, and ventral-most scales from scale row 13–origin of dorsal fin; D1, D2, D3: dorsal-most, mid-body, and ventral-most scales from origin of dorsal fin to preserved end of specimen.

Figure 9. Scales from †Lambeia pectinatus (YPM 8664). Scales are from region B3 (see Fig. 8) and have pectinated posterior and ventral margins. (a) Photograph of scales from latex peel; (b) illustration of scales.

Figure 10. Photographs of the fins of †Lambeia pectinatus (YPM 8664). (a) Pectoral fin; (b) pelvic fin; (c) anal fin. All photographs depict the latex peel of YPM 8664. Scale bars equal 5 mm.