Maghroharpes minutipunctus, Johnson, 2024

Johnson, Robert G., 2024, Devonian Harpetidae from the central and eastern Anti-Atlas, Morocco, Zootaxa 5450 (1), pp. 1-185 : 79-80

Maghroharpes minutipunctus n. sp.

Plate 23E–P

Diagnosis. Broad (sag.) brim, around 37% of cephalic length (sag.), with moderately high density of fine perforations. Eye tubercles set well away from inner margin of fringe. Transverse eye ridges, which turn anteriorly in axial furrow. Preglabellar boss barely inflated and no median girder kink. Each eye lobe with three contiguous eye lenses.

Etymology. Minuiti punctus, Latin for small holes. Named after the small brim perforations of the species.

Material and occurrence. Holotype: NHMUK It 29312, Pl. 23E–J , from “ Dicranurus Couche ”, Ihandar Formation, Pragian, Oued el Atchane, Jbel Oufatene ( Fig. 2B, Map 8, site 11); dorsal articulated exoskeleton with pygidium, enrolled . Paratype: NHMUK It 29313, Pl. 23K–P , from type locality ( Fig. 2B, Map 8, site 12), a partial dorsal exoskeleton with dorsal surface of hypostome partly exposed . Paratype: NHMUK It 29323, Pl. 22K–M , from a lower Emsian horizon, Boutiskaouine Formation , Awhare, Iferd Nou Haouar ( Fig. 2B, Map 9, site 13), dorsal exoskeleton of partial cephalon .

Other material designated M. aff. 1 minutipunctus, NHMUK It 29322, Pl. 22F–J , from the “ Ceratocephala Couche ”, Boutiskaouine Formation?, lower Emsian, Jbel Ou-Driss north ( Fig. 2B, Map 4, site 7), dorsal exoskeleton of cephalon only. M. aff 2 minutipunctus, NHMUK It 29324, Pl. 22N–Q , from coral horizon below “ Lanceaspis Couche ”, Ihandar Formation, Pragian, Jbel Ou-Driss (West) ( Fig. 2B, Map 4, site 20), a dorsal exoskeleton of partial cephalon.

Description. Cephalon ovoid and genicranium narrow, length 75% of width. Both are widest at alae. Glabella not inset, broad (width 70% of length), subcylindrical, anteriorly rounded, with granulation on dorsal surface. Axial furrows straight, barely converging anteriorly. S1 backward-sloping and starting to curve anteriorly near crest, before becoming effaced. Other muscle insertion furrows at S2, S3, and S4. Preglabellar furrow bowed upwards in anterior view. Occipital furrow shallow and medially straight in dorsal view. Occipital ring medially broadened and in lateral view, sloping posteriorly and lower than glabella anterior to S0. Occipital node small, located on anterior edge of occipital ring. L1 inflated. Alae small (tr.), parabolic in outline and anterolaterally directed. Alar furrow shallow but well-defined and axial furrow crossing junction of ala with basal lobe. Posterior border short (tr.); narrow preglabellar field (sag.).

Genal area moderately broad with faint caeca and fine pits. Eye lobes small (exsag.) (27% of width of glabella at S1); positioned away from inner margin of fringe; oval in shape; no ornamentation on dorsal surface and with three lenses each, anterior, middle and posterior lens, all contiguous or overlapping. Eye ridge narrow, curved and well-defined. Genal ridge stretching posterolaterally almost to girder. Course of inner margin of fringe across anterior of genal areas convex and marked with larger perforations across anterior boss. Anterior boss barely inflated, not joined to glabella and not reaching down to girder. No girder kink. Genal roll sloping very gently anteriorly (430), becoming a little steeper laterally (570). Faint caeca present on genal roll. Genal perforations smaller than on brim. Perforations all the same size and no row of larger perforations above girder. Girder moderately wide.

Brim profile gently concave. Brim wide (sag.), 36% of cephalic length (sag.), and moderately steeply sloping at around 220. Brim width ratio 0.86. Standardised brim perforations very fine, around 85µm in diameter. Row of larger perforations at distal and proximal edges and light caeca reaching across brim. Rim fine (under 10% of width (sag.) brim). External rim without sculpture on dorsal surface, and marginal band near vertical, with straight profile and no ridges or tubercles. Prolongations short, at around 70% of cephalic length (sag.). Internal rims subparallel in dorsal view, exterior rims curving adaxially. In lateral view, internal rims concave, with no tubercles on dorsal surface. Genal spine short. Extension of girder meeting internal rim halfway down prolongations, and dorsal surfaces of internal rim smooth. Proximal edge only of brim steepens on prolongations.

Thorax with at least 20 segments; no pits or tubercles on axial rings; pleurae not lengthening beyond compensating for narrowing (tr.) of axis posteriorly. Thorax tapering quite strongly, with shortest pleura (inner portion) being around 35% of longest. Pleural furrows U-shaped, deep and narrow. Outer portion of pleurae in line with inner. Outer portion straight with straight distal ends.

Remarks. Maghroharpes minutipunctus lacks three maghroharpid diagnostic characters shown in Table 5b. It has muscle insertion scars on the glabella at S2, S3 and S4, not present on other Maghroharpes species, the eye lobes are closer to the axial furrows and the marginal band has a straight profile rather than being concave.

Maghroharpes minutipunctus is similar to M. hammii and M. zguidensis and comparisons are given in the systematics of both species above.

M. minutipunctus aff.1 ( Pl. 22F–M ) is similar to M. minutipunctus but it has: a cephalon that in dorsal view is more oval than ovoid; a glabella that is carinate with tectiform flanks rather than rounded; a preglabellar furrow that is straight and not bowed upwards; a genal area and posterior border that are slightly wider (tr.); larger (ex sag.) eye lobes that are located close to the inner margin of the fringe, and a central lens located on the dorsal surface of the eye lobe that is larger than the other two lenses located on the lateral surface of the eye lobe. M. minutipunctus ’s anterior and posterior lenses are of equal size and all lenses are located on the lateral surface of the eye lobe. M. minutipunctus aff. 1 also has no genal ridge, no caeca on the genal roll and a brim that is narrower (sag.) and with a higher brim width ratio.

M. minutipunctus aff. 2 ( Pl. 22N–Q ) differs from M. minutipunctus by having: a glabella that has a carinate crest, tectiform flanks and a furrow at S1 that does not curve over the top of the muscle attachment area; axial furrows that converge weakly rather than being sub parallel; a preglabellar furrow that is straight in anterior view; a wider (tr.) posterior border; an inflated anterior boss and a girder kink. The genal roll of M. minutipunctus aff. 2 slopes anteriorly and laterally more steeply, there is a single row of larger perforations above girder and a narrower (sag,) brim with larger perforations and a higher brim width ratio. Also, the internal rim curves more strongly adaxially than that of M. minutipunctus .

Figures

PLATE 22. A–E Maghroharpes cf. 1 laatchanensis, Ihandar Formation, Pragian, Jbel el Otfal (Fig. 2B, Map 9, site 8), dorsal exoskeleton of partial cephalon, NHMUK It 29311. A, dorsal, B, anterior and C, lateral view. D and E, dorsal view of brim perforations and occipital node and tubercles, respectively. F–M Maghroharpes aff.1 minutipunctus, Boutiskaoine Formation? lower Emsian. F–J dorsal exoskeleton of partial cephalon, NHMUK It 29322, Jbel Ou-Driss (North) (Fig. 2B, Map 4, site 7). F, dorsal, G, anterior and H, lateral view. I, lateral and J, dorsal view of eye lobe. K–M dorsal exoskeleton of partial cephalon, paratype, NHMUK It 29323, Boutiskaouine Formation, lower Emsian, Ahware (Fig. 2B, Map 9, site 13). K, L and M, dorsal view of cephalon, brim perforations and eye lobe, respectively. N–Q Maghroharpes aff. 2 minutipunctus, Ihandar Formation Jbel Ou-Driss (West) (Fig. 2B, Map 4, site 20), dorsal exoskeleton of partial cephalon, NHMUK It 29324. N, dorsal, O, lateral and P, anterior view. Q, dorsal view of brim perforations. Scale bars shown represent 1 cm unless otherwise indicated.

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.