Fritchaspis edgecombei, Johnson, 2024

Johnson, Robert G., 2024, Devonian Harpetidae from the central and eastern Anti-Atlas, Morocco, Zootaxa 5450 (1), pp. 1-185 : 61-63

Fritchaspis edgecombei n. sp.

Plate 18A–F

Diagnosis. Cephalon widest at eyes; glabella not inset; L1 not inflated or barely inflated; occipital ring broader (sag.) than posterior border; posterior border moderately short; no preglabellar field; eye lobes large, extending to axial furrow; and no eye ridge. Course of inner margin of fringe across anterior of genal areas slightly convex; anterior boss barely inflated, attached to glabella but not reaching down to girder. No girder kink. Brim wide (sag.; 35% of cephalic length (sag.)).

Etymology. For Greg Edgecombe who provided guidance during the cladistic study and assisted in analysing the results of the parsimony analysis.

Material and occurrence. Holotype: NHMUK It 29224, Pl. 18A–F , from “Cheirurid Couche”, Er Remlia Formation , lower Emsian, Jbel Issoumour ( Fig. 2B, Map 7, site 19), a dorsal exoskeleton of cephalon only.

Description. Cephalon ovoid, genicranium narrow, widest at posterior border. Glabella has rounded flanks and slightly carinate crest, fine pitting and tubercles, and is broad with width (tr.) at S0 being around 70% of length (sag.). S1 sloping backwards and becoming effaced before curving anteriorly; no muscle attachment scar furrows at S2, S3 or S4. Axial furrows cross junction of L1 with ala and converge weakly anteriorly. Preglabellar furrow indistinct and bowed upwards in anterior view. Occipital furrow deep, straight (tr.) and broad (sag. and exsag.), broader than posterior border. Occipital ring not as broad as occipital furrow, and in lateral view, is lower than glabella anterior to S0. It has fine tubercles and pitting like that of glabella. Occipital node large, poorly inflated and located on dorsal surface rather than anterior slope. Alae laterally directed, moderately large with width (tr.) around 27% of length (sag.) of glabella anterior to S0 and length (exsag.) at axial furrow same as width (tr.). Alar furrows shallow and alar depression present. Posterior border short (tr.), just under 30% of width of occipital ring (tr.), broadening distally before joining internal rim. No preglabellar field.

Genal area broad (tr.) and without caeca or tubercles, but with fine pits. Eye lobes are oval, large (tr. and exsag.), set away from inner margin of fringe and extend to edge of axial furrow. Three eye lenses per eye lobe, anterior and posterior lenses oval and of equal size and third lens much smaller, subcircular, positioned high up between other two lenses ( Pl. 18F ). No eye or genal ridge. Inner margin of fringe convex across anterior of genal areas, and across anterior boss, its path not marked by perforations larger than those on genal roll directly below. Anterior boss barely inflated, joined to glabella and only just reaches down to girder, which is narrow and without kink. Genal roll sloping gently anteriorly (490) and laterally (550). Perforations on genal roll smaller than those on brim, and genal roll lacks caeca. Brim very broad (sag.), 35% of cephalic length (sag.), straight in profile, gently sloping (120) and with caeca reaching on to edge of brim posterolaterally. Standardised diameter of brim perforations larger, at nearly 200 μm. Brim width ratio is 0.66. External rim stout, dorsal surface near horizontal and marginal band vertical, rather than sloping down under cephalon. Dorsal surface of rim overhangs marginal band. Prolongations moderately short (exsag.), around 80% of cephalic length (sag.). In dorsal view, exterior and internal rims curve adaxially posteriorly and in lateral view, internal rim in lateral view concave and meets external rim at end of prolongation. Extension of girder meets internal rim about one third of way down prolongation. Whole brim steepens gently on prolongations to less than vertical and no row of larger perforations below internal rim. Internal rim and external rims on prolongations have tubercles on dorsal and distal surfaces, respectively. Genal spine short.

Hypostome, thorax and pygidium unknown.

Remarks. Fritchaspis edgecombei lacks two of the genus’s diagnostic characters shown in Table 5a: the posterior border is narrower (tr.) being about 30% of the width(tr.) of the occipital ring and the spaces between the brim perforations are not inflated.

Fritchaspis edgecombei differs from F. wendti ( Feist 2018) in having a slightly narrower genicranium, a glabella which is not inset and has rounded not tectiform flanks; no furrows at S2 or S3; a base lobe which is not inflated or barely inflated; axial furrows less tapered anteriorly; a narrower (sag.) occipital ring, which is narrower than posterior border and, in lateral view, higher than glabella anterior to S0. Also, F. edgecombei has a shorter (tr.) posterior border; no preglabellar field; eye lobes which extend to axial furrow and no eye ridge. Inner margin of fringe across the anterior of genal area is convex rather than straight or concave, and the anterior boss does not reach down to girder, there is no weak girder kink and the girder is narrower. The genal roll, both anteriorly and laterally, is not so steeply sloping and the brim much wider (sag.), without caeca and with larger brim perforations.

The main differences between F. edgecombei and the type species F. montagnei are that F. montagnei ’s cephalon is widest at the alae, not at the eyes, and the glabella is inset and has a small central tubercle towards its anterior. Also, the glabella is not carinate, S1 is not effaced before curving anteriorly near the crest, and it has muscle insertion scars at S2 and S3. Its preglabellar furrow is distinct and it has a wide preglabellar field, unlike F edgecombei , which has none. In lateral view, F. montagnei ’s occipital ring is higher than the glabella anterior to S0. Eye lobes do not extend to the axial furrow and have two eye lenses each, not three. F. montagnei has a narrow eye ridge, and the inner margin of fringe across the anterior of the genal area is straight not convex and its path across anterior boss is marked by perforations that are bigger than those on the boss immediately below. The anterior boss is not joined to the glabella, is more inflated and reaches down to the girder, which is weakly kinked. The girder of F. montagnei is wider, the brim concave (sag.) straight laterally and 20% narrower (sag.) than that of F. edgecombei . The brim of F. montagnei also has caeca, with inflated spaces between the brim perforations.

The holotype of F. edgecombei is a well preserved complete cephalon despite the damage to the anterior of the exterior rim across the sagittal line. It is also of a size that would indicate that it belonged to a well-developed holaspid and appears to be symmetrical. Differences with F. wendti , the species it is most similar to are significant. On this basis the species has been erected without the support of paratypes.

Genus Kielania Vaněk 1963

Type species. Harpes waageni Prantl & Přibyl, 1954 from Prokop Limestone, (Pragian) Praha-Malá Chuchle, Czech Republic.

Emended diagnosis. Cephalon strongly vaulted. Occipital furrow medially straight (tr.). Alae depression absent. Eye lobe short (exsag.), between 15% and 31% width (tr.) of glabella at S0. Course of inner margin of fringe across anterior of genal area convex. Girder moderately wide (sag. and exsag.), between 2.2% and 3% of width (tr.) of genicranium. Brim barely convex to moderately convex and sloping steeply at between 250 and 450. Standardised brim perforations moderately fine, less than 150 μm. Exterior rim fine and marginal band sloping down under cephalon. Thorax of up to 16 segments.

Discussion. Kielania has been used as a genus for nearly all species of harpetids with convex brims, with little attention being paid to other morphological features. Here, the genus has been reduced to include seven species and Prantl & Přibyl’s (1954) original diagnosis has been emended to reflect this. The former members of Kielania that have been transferred are as follows: K. superna Maksimova, 1979 to “ Lioharpes ” s. l.; K. convexa ( Hawle & Corda, 1847) and K. obuti Přibyl and Vaněk, 1986 to Stoloharpes n. gen; K. kayseri ( Novák,1890) to Helioharpes . K. novaki ( Prantl & Přibyl, 1954) and K. praecedens ( Prantl & Přibyl, 1954) to Declivoharpes .

Kielania is similar to Stoloharpes n. gen. in that most of its species have convex brims, but differs in having a cephalon that is widest posterior to the midpoint between the eyes lobes and the alae, rather than at the alae, and which is not pyriform in outline; a glabella that has a rounded rather than carinate crest; a broader genicranium; a distinct preglabellar furrow; a preglabellar field; a genal roll that is more steeply-sloping anteriorly; a brim that does not steepen strongly on the prolongations and up to 16 thoracic segments, not 24 as is the case in Stoloharpes .

Kielania species included in the study and are shown together with their interspecies relationships in Fig. 10b . Kielania ovalis Lisogor, 1965 is not included in the study but remains in the genus. The range of the Kielania genus is from Lochkovian to upper Emsian.

Figures

FIGURE 10a. Lioharpes and Maghroharpes from tree 1 of 60 found using seed 7

PLATE 18. A–F Fritchaspis edgecombei n. sp., dorsal exoskeleton of cephalon only, NHMUK It 29224, from “Cherurid Couche”, Er Remlia Formation, lower Emsian, Jbel Issoumour (Fig. 2B, Map 7, site 19). A, dorsal, B, antero-dorsal, C, anterior and D, lateral view. E, dorsal view of brim perforation and F, lateral view of eye lobe. G–N Maghroharpes hammii n. sp., dorsal exoskeleton, thorax enrolled, holotype, NHMUK It 29292, from an horizon below the “Dicranurus Couche”, Ihandar Formation, Pragian, Jbel Oufatene (Fig. 2B, map 8, site 21). G, dorsal, H, anterior, J, lateral and I, posterior view. L, dorsal view of brim perforation, N, lateral view of glabella and muscle insertion scars and M, dorsal view of cuticle on glabella, genal area, ala, occipital ring and posterior border. Scale bars shown represent 1 cm unless otherwise indicated.