Maghroharpes zguidensis, Johnson, 2024

Johnson, Robert G., 2024, Devonian Harpetidae from the central and eastern Anti-Atlas, Morocco, Zootaxa 5450 (1), pp. 1-185 : 75-76

Maghroharpes zguidensis n. sp.

Plate 24A–L

Diagnosis. Cephalon widest just anterior to alae, glabella carinate, and no eye ridges. Anterior boss barely inflated and joined to glabella by gentle swelling in preglabellar field. Genal roll sloping anteriorly at under 500. Brim narrow (sag.), at 28% of length of cephalon (sag.); and very fine brim perforations with standardised diameter of ≈70µm. Prolongations short, ≈ 66% of length (sag.) of cephalon. Internal and external rims robust, curving adaxially on prolongations.

Etymology. Named after the town near the type locality, Foum Zguid.

Material and occurrence. Holotype: NHMUK It 29325, Pl. 24 A–E , from basal limestones of the Merzâ Akhsai Formation?, Pragian, S.W. of Foum Zguid ( Fig. 2A, Map 2, site 1), dorsal exoskeleton of cephalon only . Paratypes: NHMUK It 29326, Pl. 24 F–I , and NHMUK It 29327, Pl. 34J–K , both from type locality ( Fig. 2A, Map 2, sites 2 and 3, respectively), dorsal exoskeletons of cephala only.

Other material: Maghroharpes cf. z guidensis, NHMUK It 29328, Pl. 31L–N , from a Pragian horizon, Merzâ Akhsai Formation? el Ayoun, Tata ( Fig. 2A, Map 1, site 1).

Maghroharpes aff. zguidensis, NHMUK It 29287, Pl. 23A–D , from an upper Pragian horizon, Ihandar formation, at the foot of bou Lachrhal (Fig. B, Map 9, site 5), dorsal exoskeleton of cephalon.

Description. Cephalon sub oval, widest (tr.) just anterior to alae. Genicranium narrow (length 77% of width), widest at posterior border. Glabella carinate; L1 barely inflated; S1 very shallow, becoming effaced before curving anteriorly near crest; and no furrows at S2, S3 or S4. Axial furrows convex and converging weakly anteriorly. Preglabellar furrow barely distinct, occipital furrow deep and medially straight. Occipital ring same width (sag.) as width of posterior border (exsag.), sloping posteriorly and lower than glabella anterior to S0. Occipital node small, at anterior edge of dorsal surface of occipital ring. Alae small (tr.) and laterally directed. Alar furrow shallow and well defined, and no alar depression. Posterior border moderately short (tr.) and preglabellar field narrow (sag.).

Genal area moderately broad (tr.) and without caeca. Eye lobes oval, inflated and located close to inner margin of fringe. There are two eye lenses per eye lobe and no pitting or tubercles on their dorsal surfaces. No genal ridge or eye ridge, and course of inner margin of fringe across anterior of genal area is straight. Boss barely inflated but reaches down to girder, joined to glabella by a ridge narrower than glabella. Genal roll sloping gently anteriorly (≈ 490), moderately steeply laterally (≈ 620). Inner fringe narrowing moderately in lateral view. Caeca on genal roll and genal roll perforations same size as those on brim. Girder moderately wide and girder kink weak.

Brim concave, narrow (sag.), moderately to moderately steeply sloping (≈ 200). Brim width ratio 0.88 and standardised brim perforations very fine, with a diameter around 70µm. Light caeca across brim. Marginal band is near vertical, concave and with ridges top and bottom, but no tubercles. Prolongations short (exsag.), at 65% of cephalic length (sag.). Internal and external rims curving adaxially. Internal rim concave in lateral profile. Genal spine short, following curve of external rim. Extension of girder meeting internal rim nearly two thirds of way down prolongation. No larger perforations under internal rim and rim on prolongation only steepening along proximal edge.

Remarks. Maghroharpes zguidensis has two characters which do not comply with the chosen diagnostics of the genus as shown in Table 5b —inner margin of the fringe across the anterior of the genal area is straight rather than convex, and the extension of the girder meets the internal rim two-thirds of the way down the prolongation rather than half-way down.

Maghroharpes zguidensis is similar to M. minutipunctus but differs in having: a cephalon that is oval rather than ovoid shaped; a glabella which is carinate and has no muscle insertion furrows at S1, S2, S3 and S4; a much less distinct preglabellar furrow; a deeper occipital furrow; an occipital ring that is not medially broadened (sag.); a wider (tr.) posterior border; alae laterally not anterolaterally directed; the genal area without the faint caeca present on M. minutipunctus ; larger eye tubercles (exsag.) set close to the inner margin of the fringe, with two rather than three eye lenses each; no genal or eye ridge, unlike M. minutipunctus where both ridges are well defined; an anterior boss that is connected to the glabella and reaches down to a well-defined girder kink; perforations on the genal roll the same size as on the brim rather than smaller, and the brim is 20% narrower (sag.) than that of M. minutipunctus ; a more robust external rim; a marginal band that has a ridge top and bottom rather than none; internal rims which in dorsal view curve adaxially rather than being subparallel; and an extension to the girder that meets the internal rim two thirds of the way down the prolongation, rather than halfway down as in the case of M. minutipunctus .

Maghroharpes cf. zguidensis ( Pl. 31L–N ) differs from M. zguidensis in having an occipital ring that is medially broadened, eye lobes with three lenses rather than two and a wider brim (sag.) with a 10% lower brim width ratio.

Maghroharpes aff. zguidensis ( Pl. 23A–D ) is similar to M. zguidensis but differs in having: a glabella with a rounded rather than carinate crest; a wider occipital furrow; a broadened occipital ring; a very shallow and distallyeffaced alar furrow; a posterior border that is 70% wider (tr.) in relation to the width (tr.) of the occipital ring than that of M. zguidensis ; an anterior boss that does not reach down to the girder; the girder lacking a kink; the genal roll sloping more steeply anteriorly; the perforations on genal roll smaller than those on brim; the brim 18% wider (sag.), the brim width ratio 15% lower and brim perforations more than twice the diameter of those on the brim of M. zguidensis ; internal rims on prolongations subparallel rather than curving adaxially; genal spine that follows the curve of external rim, and the extension to its girder meeting half way down the prolongation rather than two thirds of the way down, as in the case of M. zguidensis .

Figures

PLATE 23. A–D Maghroharpes aff. zguidensis, dorsal exoskeleton of partial cephalon, holotype, NHMUK It 29287, from Ihandar Formation, bou Lachrhal (Fig. 2B, Map 9, site 5). A, dorsal, B, anterior and C, lateral view. D, dorsal view of brim perforations. E–P Maghroharpes minutipunctatus n. sp. E–J holotype, NHMUK It 29312, from “Dicranurus Couche”, Ihandar Formation, Pragian, ElAtchane, Jbel Oufatene (Fig. 2B, Map 8, site 11), dorsal exoskeleton. E, dorsal, F, anterior and G, lateral view. H, lateral view of glabella (uncoated), I, dorsal view of brim perforations and J, lateral view of eye lobe. K–P paratype, NHMUK It 29313, from type locality (Fig. 2B, Map 8, site 12), partial dorsal exoskeleton with pygidium enrolled. K, dorsal and L, lateral view. M, N, O, and P, dorsal view of pleurae, brim perforations, lower lamella and hypostome, respectively. Scale bars shown represent 1 cm unless otherwise indicated.

PLATE 24. A– L Maghroharpes zguidensis n. sp., Merzâ Akhsai Formation?, Pragian, Foum Zguid. A–E dorsal exoskeleton of partial cephalon, holotype, NHMUK It 29325 (Fig. 2A, Map 2, site1). A, dorsal, B, anterior and C, lateral view. D, dorsal view of brim perforations. F– I dorsal exoskeleton of cephalon, paratype, NHMUK It 29326, from type locality (Fig. 2A, Map 2, site 2). F, dorsal, G, lateral and H, anterior view. I, dorsal view of brim perforations. J–L dorsal exoskeleton of cephalon, paratype, NHMUK It 29327, from type locality (Fig. 2A, Map 2, site 3). J, dorsal, K, anterior and L, lateral view. Scale bars shown represent 1 cm unless otherwise indicated.

PLATE 31. A–E Maghroharpes aff. ihmadii, dorsal exoskeleton of partial cephalon, NHMUK It 29305, from an upper Pragian horizon, Ihandar Formation, bou Lachrhal (Fig. 2B, Map 9, site 4). A, dorsal, B, lateral and C, anterior view. D, lateral view of eye lobe and E, dorsal view of brim perforations. F–K Maghroharpes cf. forteyi, dorsal exoskeleton of partial cephalon, NHMUK It 29284, from top of the Pragian, Ihandar Formation, Oued el Atchane, Jbel Oufatene (Fig. 2B, Map 8, site 20). F, dorsal, G, anterior and H, lateral view. I, lateral view of eye lobe, J, dorsal view of brim perforations and K, pits on axial node. L–N Maghroharpes cf. zguidensis, dorsal exoskeleton of cephalon, NHMUK It 29328, from MerzâAkhsai Formation?, Pragian, Douar Laayoune, Tata (Fig. 2B, Map 1, site 1). L, dorsal and M, lateral view. N, dorsal view of brim perforations. Scale bars shown represent 1 cm unless otherwise indicated.

PLATE 34. A–I Eskoharpes sicarius n. sp., from Type horizon, lower Frasnian, Bouia, 7 km SE of Jorf (Fig. 2B, Map 6, site 5). A–E paratype, NHMUK it 29256 (2), dorsal exoskeleton of partial cephalon only. A, dorsal view, B, lateral view, C, anterior view, D, dorsal view of eye lobe and eye ridge and E, anterior dorsal view of brim perforations. F–G paratype, NHMUK it 29256 (5), dorsal exoskeleton partial cephalon. F, dorsal, G, lateral view of posterior of prolongation including genal spine. H paratype, NHMUK it 29256 (4), dorsal exoskeleton of partial cephalon and disarticulated thorax, dorsal view. I paratype, NHMUK it 29256 (1&7), dorsal exoskeleton of partial concealed cephalon, dorsal view. Scale bars shown represent 1 cm unless otherwise indicated.