DIPNOI MÜLLER, 1845

Friedman, Matt, 2007, The interrelationships of Devonian lungfishes (Sarcopterygii: Dipnoi) as inferred from neurocranial evidence and new data from the genus Soederberghia Lehman, 1959, Zoological Journal of the Linnean Society 151 (1), pp. 115-171 : 120-121

DIPNOI MÜLLER, 1845

RHYNCHODIPTERIDAE MOY- THOMAS, 1939 SOEDERBEGHIA LEHMAN, 1959

Remarks: There are two nominal species of Soderberghia: the type species, Soederberghia groenlandica Lehman, 1959 , which is from the Famennian of East Greenland and the focus of this paper, and the attributed species S. simpsoni Ahlberg et al., 2001 , which is known from the Frasnian Mandagery Sandstone of New South Wales, Australia. All additional material attributed to this genus is of Famennian age, and includes a lower jaw from Belgium ( Clément & Boisvert, 2006; these authors identify an incomplete postcranium as cf. Soederberghia ) and two incomplete skull roofs from the Catskill Formation of Pennsylvania, USA, and the Cloghnan Shale of New South Wales, Australia, respectively.

The Catskill and Cloghnan Shale skulls display derived characters of S. groenlandica , so their provisional placement in this species ( Ahlberg et al., 2001) is accepted here. The relationship of additional Soederberghia material, particularly that of S. simpsoni , to the type species is less clear. While the phenetic similarity between S. simpsoni and S. groenlandica is impressive, Ahlberg et al. (2001) cited only two derived characters that might indicate that these genera form a clade to the exclusion of other known ‘rhynchodipterids’: (1) a single bone in the place of bones 1b and 2, and (2) contact between the E- and Lbones. The systematic significance of these features must be interpreted cautiously, because the conclusion that these same character states are absent from Rhynchodipterus is based on an inaccurate reconstruction of sutural patterns in this genus ( Schultze, 1969). The head in the only known specimen of Rhynchodipterus is preserved as the mould of the visceral surface of the skull, and most sutures are, at best, vaguely defined. Schultze (1969) reconstructed separate bones 1b and 2, but the ‘suture’ between these putative ossifications is not convincing (pers. obs. of E 1892.2 A, B). It seems more prudent to regard the bone pattern in this region of Rhynchodipterus as either uncertain or identical to that found in Soederberghia . Similarly, the specimen of Rhynchodipterus presents no clear indication that the relationship between the E- and L-bones differed in any meaningful way from S. groenlandica and S. simpsoni (contra Schultze, 1969). Ahlberg et al. (2001) had already expressed doubt about this last character as a synapomorphy of Soederberghia because it is present in Fleurantia . Similar arrangements can also be found in Jarvikia ( Lehman, 1959) , Andreyevichthys (Krupina, 1987) and Phaneropleuron ( Westoll, 1949) . If some or all of these genera are shown to constitute a clade with Soederberghia (cf. Friedman, 2005), then contact between the E- and L-bones would be more reasonably interpreted as a synapomorphy of that larger radiation rather than a feature uniting the two nominal species of Soederberghia as sister taxa.

It should be clear from this discussion that the validity of the attribution of S. simpsoni to Soederberghia can only be tested through a comprehensive phylogenetic analysis. This paper considers only neurocranial data, which is unknown for S. simpsoni , and therefore cannot meaningfully address this question. I have therefore not included a new diagnosis for Soederberghia and choose to withhold conclusions on the content of this genus until more extensive studies have been executed.

SOEDERBERGHIA GROENLANDICA LEHMAN, 1959

( FIGS 1–10 , 12–13 )

For synonymy, see Schultze (1992c).

Diagnosis: Long-snouted, denticle-bearing lungfish differing from other ‘rhynchodipterids’ in the following combination of characters: bones 4 and 5 excluded from the orbit; width of the dermal cheek exceeds the maximum diameter of the orbit.

Holotype: MGUH VP 3036 , complete dermal skull roof. The counterpart to this specimen is catalogued as MGUH VP 3035 .

Type locality: Late Devonian (middle [latest Fa2a to Fa2b] to early late [Fa2d] Famennian; Marshall et al., 1999) Aina Dal Formation of the Celsius Bjerg Group, Nathorst Bjerg at an elevation of 372 m, Gauss Halvø, East Greenland.

Horizon and distribution: Famennian of North America, East Greenland and Australia ( Ahlberg et al., 2001).

Referred material: A list of all referred specimens of Soederberghia groenlandica examined during the course of this study is given above in Material Examined.

Figures

Figure 1. Soederberghia groenlandica, otoccipital region of neurocranium in right lateral view (MGUH VP 28400). A, specimen photograph; B, interpretive drawing. Light grey shading in B corresponds to areas of matrix with bone impressions, while dark grey regions represent matrix. Diagonal hatching indicates damaged bone surface. Large arrow indicates view illustrated in Figure 4. Shaded regions in inset drawing indicates regions preserved in A and B. Scale bar represents 20 mm.

Figure 2. Soederberghia groenlandica, otoccipital region of neurocranium in left lateral view (MGUH VP 28400). A, specimen photograph; B, interpretive drawing. Light grey shading in B corresponds to areas of matrix with bone impressions, while dark grey regions represent matrix. Diagonal hatching indicates damaged bone surface. Large arrow indicates view illustrated in Figure 4. Shaded regions in inset drawing indicates regions preserved in A and B. Scale bar represents 20 mm.

Figure 3. Soederberghia groenlandica, reconstructed braincase in left lateral view based on MGUH VP 28400. Diagonal hatching indicates unfinished articular area. Shaded regions in inset drawing indicates regions depicted. Scale bar represents 20 mm.

Figure 4. Soederberghia groenlandica, interpretive drawing of a cross-section through the occipital region (MGUH VP 28400). Dark shading represents matrix, while diagonal hatching indicates damaged surface. View is that indicated in Figures 1, 2 by bold arrow. Scale bar represents 10 mm.

Figure 5. Soederberghia groenlandica, visceral surface of dermal skull roof with impressions of the otoccipital region of the braincase (MGUH VP 28400). Anterior is to the left, midline is to the top. A, specimen photograph; B, interpretive drawing. Light grey shading in B corresponds to areas of matrix with bone impressions, while dark grey regions represent matrix. Diagonal hatching indicates damaged bone surface. Scale bar represents 20 mm.

Figure 6. Soederberghia groenlandica, mould of the visceral surface of the dermal skull roof (MGUH VP 3036). Anterior is to the top. Asterisk marks orbit, while regions visible in specimen photograph are shaded in inset drawing. Scale bar represents 20 mm.

Figure 7. Soederberghia groenlandica, visceral surface of dermal skull roof with endoskeletal ossifications of the ethmoid region (MGUH VP 28398). Anterior is to the top. A, specimen photograph; B, interpretive drawing. Light grey shading in B corresponds to areas of matrix with bone impressions, while dark grey regions represent matrix. Diagonal hatching indicates damaged bone surface. Scale bar represents 20 mm.

Figure 8. Soederberghia groenlandica, latex peel of negative preparation of a palate in ventral view (MGUH VP 28397; same individual as in Figs 9, 10, 12). Anterior is to the top. A, specimen photograph; B, interpretive drawing. Dark grey regions in B represent matrix, while diagonal hatching indicates damaged bone surface. Scale bar represents 20 mm.

Figure 9. Soederberghia groenlandica, latex peel of negative preparation of an isolated left entopterygoid in ventral view (MGUH VP 28397). Anterior is to the top. A, specimen photograph; B, interpretive drawing. Dark grey shading in B indicates matrix. Scale bar represents 20 mm.

Figure 10. Soederberghia groenlandica, close-up of latex peel of negative preparation of palate (predominantly right entopterygoid) in ventral view (MGUH VP 28397). Anterior is to the top. Scale bar represents 10 mm.

Figure 12. Soederberghia groenlandica, latex peel of negative preparation of right entopterygoid in dorsal view (MGUH VP 28397). Anterior is to the right. A, specimen photograph; B, interpretive drawing. Dark grey shading in B represents matrix, while diagonal hatching indicates damaged bone surface. Shaded area in inset drawing indicates region preserved in A and B. Scale bar represents 20 mm.