Lioharpes morocconensis, Johnson, 2024

Johnson, Robert G., 2024, Devonian Harpetidae from the central and eastern Anti-Atlas, Morocco, Zootaxa 5450 (1), pp. 1-185 : 56-57

Lioharpes morocconensis n. sp.

Plate 11A–M

Diagnosis. Glabella anteriorly tapered with no carination and axial furrows convex. S1 sloping backwards, before curving forward. Occipital furrow medially bent forward, eye ridge poorly defined. Genal roll with caeca and brim perforations moderately large and becoming smaller away from girder. Well-developed caeca crossing brim. Genal prolongations moderately short and internal rims subparallel.

Etymology. Country of type locality.

Material and occurrence. Holotype: NHMUK It 29271 (1), Pl. 11F–J , from a lower Emsian horizon Boutiskaouine Formation, Jbel el Otfal ( Fig. 2B, Map 9, site 6), a partial dorsal exoskeleton of cephalon . Paratype: NHMUK It 29272, Pl. 11A–E , from type locality and horizon ( Fig. 2B, Map 9, site 17), dorsal exoskeleton of cephalon only . Paratype: NHMUK It 29271 (2), Pl. 11K–L ), from type locality (site 6), partial dorsal exoskeleton of cephalon .

Other material: Lioharpes cf. morocconensis, NHMUK It 29273, Pl. 12A–F , from an lower Emsian horizon, Seheb El Rhassel Group, 28.3 km S.S.W. of Rissani ( Fig. 2B, Map 14, site 10), dorsal exoskeleton of partial cephalon.

Description. Cephalon and genicranium widest at mid-point between eye lobes and alae. Glabella anterior to S0 broad, crest rounded with granulation and fine pitting, S1 slanting posteriorly and starting to curve anteriorly near crest, furrows at S2, S3 and S4 not present. Preglabellar furrow distinct and straight (tr.) in anterior view; occipital furrow deep and just broader (sag.) than posterior border (exsag.). Occipital ring same height in lateral view as glabella anterior to S0 and with very fine tubercles on dorsal surface. Occipital node small located on anterior slope of occipital ring. L1 not inflated, axial furrow not crossing junction of ala with L1, ala size (tr.) large, width (tr.) 30% of glabella (tr.) at S1, and moderately wide with width (tr.) 80% of length (exsag.). Alar furrow deep, well defined, interalar ridge, furrow and depression present, alae laterally directed. Posterior border moderately wide (tr.), over 40% of width (tr.) of occipital ring and preglabelar genal area (sag.) 22% of width (tr.).

Genal area moderately broad, width (tr.) 62% of length (exsag.), with caeca and pits. Eye lobes large (exsag.), over 31% of glabella width at S0 and with very fine tubercles on dorsal surface. Anterior and posterior eye lenses ovoid and of equal size, central lens much smaller, subcircular and set in between and slightly higher than anterior and posterior lenses. Eye location ratio 0.78, eye ridge indistinct and no genal ridge. Course of inner margin of fringe across anterior of genal area straight, anterior boss barely inflated, reaching down to weak girder kink. In lateral view, slope (sag.) between inner margin of fringe and girder is gentle (470). Genal roll strongly convex, barely sloping at internal margin of fringe but steepening sharply to become near vertical at girder. Laterally, genal roll sloping moderately steeply at 630. Genal roll with caeca and perforations smaller than those on brim. Girder moderately narrow.

Brim concave, sloping (sag.) at under 100 and moderately wide, width (sag.) 31% of cephalic length (sag.). Brim perforations decrease for short distance away from girder and diameter of standardised brim perforations on central part of brim (sag.) just under 200μm. Brim on prolongation steepening posteriorly along inside edge and brim width ratio 0.82. Rim stout, without tubercles on dorsal surface, and marginal band near vertical with ridge around top and bottom and fine scattered tubercles in between. Prolongations moderately short (exsag.), about 80% of cephalic length (sag.). In dorsal view, internal rims subparallel; in lateral view, concave. External rim curving gently adaxially (dorsal view) and upwards (lateral view) to meet internal rim at end of prolongation, which lacks genal spine. Dorsal surface of internal rim with tubercles, with row of large perforations below rim.

Thorax, pygidium and hypostome unknown.

Remarks. Lioharpes morocconensis complies with all the proposed diagnostic characters of its genus as shown in Table 5a, except that the width (tr.) of its posterior border is about 45% of the width (tr.) of the occipital ring, wider than the upper diagnostic range of 31% to 40%.

Lioharpes morocconensis is also very similar to L. galea , but differs in having: the genicranium widest at midpoint between eye lobes and alae rather than at posterior border; alae laterally directed rather than anterolaterally; posterior border wider (tr.);the anterior boss reaches down to the girder that is weakly kinked, unlike in L. galea ; smaller brim perforations which become smaller towards centre of brim; and shorter prolongations with internal rims subparallel rather than curving adaxially.

Lioharpes cf. morocconensis ( Pl. 12A–F ) differs from L. morocconensis in having: an occipital ring whose top in lateral view is lower than the top of the glabella anterior to S0; genal areas more finely pitted; shallower alar furrows; genal roll much less convex (sag.); brim slightly steeper (sag.) with more pronounced caeca and the whole brim steepening on prolongations, not just along the proximal edge; prolongations shorter with girder extension meeting internal rim a little further down prolongation.

Figures

PLATE 11. A–M Lioharpes morocconensis n. sp. A–E dorsal exoskeleton of cephalon only, paratype, NHMUK It 29272, from a lower Emsian horizon, Boutiskaouine Formation, Jbel el Otfal (Fig. 2B, Map 9, site17). A, dorsal, B, anterior and C, lateral view. D, lateral view of eye lobe and E, dorsal view of brim perforation. F–J dorsal exoskeleton of cephalon only, holotype, NHMUK It 29271 (1), from type locality and horizon (Fig. 2B, Map 9, site 6). F, dorsal, G, lateral and H, anterior view. I, dorsal view of glabella and J dorsal view of brim perforation. K–L dorsal exoskeleton of a partial cephalon, paratype, NHMUK It 29271 (2)), on same plate as holotype, K, dorsal view and L, lateral view of eye lobe. M, dorsal view of NHMUK It 29271 (1 and 2) plate. Scale bars shown represent 1 cm unless otherwise indicated.

PLATE 12. A–F Lioharpes cf. morocconensis, from a lower Emsian horizon, Boutiskaouine Formation, 28.3 km SSW of Rissani (Fig. 2B, Map 14, site 10), dorsal exoskeleton of partial cephalon, NHMUK It 29273. A, dorsal, B, anterior and C and D, lateral view. E, lateral view of eye lobe and F, dorsal view of brim perforation. G–M Lioharpes ammari n. sp., from an upper Emsian horizon, Tazoulait Formation, North flank of Jbel Ou-Driss (Fig. 2B, Map 4, site 9), dorsal exoskeleton with pygidium enrolled, holotype, NHMUK It 29263. G, dorsal, H, anterior and I, lateral view. J and K, dorsal and lateral views, respectively, of eye lobe. L and M, dorsal view of brim perforations and exterior rim, respectively. Scale bars shown represent 1 cm unless otherwise indicated.