Maghroharpes azmamarensis Johnson 2024, n. sp.
Creators: name: Johnson, Robert G.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Trilobita
Harpetida
Harpetidae
Maghroharpes
Maghroharpes azmamarensis

description: Maghroharpes azmamarensis n. sp.   
Plates 29E–J, O, 30A–E  
 Diagnosis. Cephalon nearly ovoid; glabella inset, broad, strongly vaulted and with convex axial furrows, converging anteriorly. Genal roll gently sloping (sag. and exsag.) and without caeca. Axial and alar furrows deep; preaxial furrows forming circular depressions, crossing inner margin of fringe. Eye lobes inflated and with three eye lenses each. Brim width ratio 0.80 to 0.85, and diameter of standardised brim perforations moderate to large (>145 μm).   
 Etymology. Named from type locality: Azmamar.   
 Material and occurrence. Holotype: NHMUK It 29281, Pl. 29E–J, from coral horizon at or near the “Couche Rouge” horizon at the top of the Pragian, Ihandar Formation, Azmamar, Oued el Atchane, Jbel Oufatene (Fig. 2B, Map 8, site 18), dorsal exoskeleton of cephalon only. Paratypes: NHMUK It 29282 (1 and 2), Pl. 30A–E and 39O, from type locality and horizon (Fig. 2B, Map 8, site 19), A–E dorsal exoskeleton of cephalon and, O, lower lamella on same slab.   
 Other material: Maghroharpes cf. azmamarensis: NHMUK It 29285, Pl. 30F–K, from coral horizon at or near the “Couche Rouge” horizon at the top of the Pragian, Ihandar Formation, Azmamar, Oued el Atchane, Jbel Oufatene (Fig. 2B, Map 8, site 17), dorsal exoskeleton of cephalon. NHMUK It 29286, Pl. 30L–O, from an upper Pragian horizon, Ihandar Formation, Maharch, Jbel Mrakib (Fig. 2B, Map 9, site 14), dorsal exoskeleton of partial cephalon.   
 Description. Cephalon ovoid, widest at midpoint between eyes and alae. Genicranium broad, widest at posterior border. Glabella inset, strongly vaulted, very broad with convex flanks, rounded crest and tubercles. Axial furrows convex and converging strongly anteriorly. L1 inflated, S1 sloping posteriorly and effaced before curving anteriorly near crest. No furrows at S2–S4. Preglabellar furrow straight in anterior view, and preglabellar field narrow and well defined. Occipital furrow narrow and medially straight. In lateral view, occipital ring sloping posteriorly and same height as glabella anterior to S0; not medially broadened and has sculptural tubercles. Occipital node large and well inflated. Alae small (tr.) and laterally directed. Alar depression present and posterior border moderately short.   
 Genal area moderately broad, with no caeca or tubercles. Large eyes (exsag.), set close to inner margin of fringe. Eye location ratio around 0.90, and tubercles and pitting on eye lobes. Each eye lobe with 3 eye lenses, anterior and posterior largest and small central lens located high up between other two lenses. Eye ridge not well defined and internal margin of fringe convex across anterior of genal area. Preaxial furrows broad, not converging and forming depressions where they cross at inner margin of fringe. Glabella, preglabellar field, genal area and dorsal surface of eye lobes have fine, dense pitting. Anterior boss barely inflated, reaching down to weak girder kink. Genal roll sloping very gently anteriorly (≈ 350) and moderately steeply laterally (≈ 550). In lateral view, fringe narrows strongly posteriorly. Perforations on genal roll smaller than on brim, with row of larger perforations immediately above girder and across anterior boss at inner margin of fringe. No caeca. Girder moderately wide (≈ 2.6% of width (tr.) of genicranium).   
Brim concave, not steeply sloping (≈15%) and with width (sag.) 30% of cephalic length (sag.). Brim width ratio 0.80. Standardised brim perforations 147µm, with row of larger perforations at proximal and distal edges of brim. Density of perforations on brim around 15 per square mm on standardised brim. Light caeca across brim. External rim stout, with rim suture running around centre of dorsal surface. Marginal band near vertical, concave, with tubercles and ridge around top and bottom. Length (exsag.) of prolongations around 75% of cephalic length (sag.). Internal and external rims curve adaxially and internal rims are concave in lateral view. Posterior border and internal rims thicker than exterior rim in dorsal view. Dorsal surface of internal rim sparsely covered by small tubercles. Girder extends onto prolongation, to meet internal rim halfway down prolongation. Proximal edge of brim steepening on prolongations, and prolongations terminate in spine carried on lower lamella.  
No hypostomes, thoracic or pygidial sclerites are known.  
 Remarks. Maghroharpes azmamarensis lacks one of the diagnostic characters of its genus as shown in Table 5b, having an alar depression, which is lacking in most other members of the genus.   
NHMUK It 29282 is very similar to the holotype but lacks bilateral symmetry, with one prolongation longer than the other, which may be the result of a teratological fault.  
 Maghroharpes azmamarensis closely resembles M. oufatenensis but differs in having: an ovoid rather than oval cephalon, which is widest at midpoint between the eye lobes and the alae, not at the alae as in the case of M. oufatenensis; an inset, carinate glabella with tubercles on its dorsal surface; eye lobes with pitting and tubercles on their dorsal surfaces and 3 lenses each the anterior and posterior lenses of equal size and the third lens between the other two, much smaller, while M. oufatenensis ’s eye lobes lack tubercles and pitting and have only two lenses, the anterior lens being the largest; a low poorly defined eye ridge, which is absent on M. oufatenensis; a genal roll that slopes gently anteriorly at around 360 and laterally at around 540, compared to 550 and 720 respectively, in the case of that of M. oufatenensis; the brim sloping at around 150 with caeca that stretch right across it, while the brim of M. oufatenensis slopes at 70 and has caeca does not reach far across it; internal rims that curve adaxially and are not subparallel; and genal spines that follow the curve of external rim rather than being set at an oblique angle, as they are in the case of M. oufatenensis.   
 Maghroharpes cf.1 azmamarensis (Pl. 40 A–E) specimen NHMUK It 29285 differs from M. azmamarensis in having a wider (tr.) cephalon and genicranium, and shorter (exsag.) prolongations. The exoskeleton is not well preserved but otherwise seems similar to the holotype.   
 Maghroharpes cf.2 azmamarensis (Pl. 30L–O) specimen NHMUK It 29286 is similar to M. azmamarensis, but differs in having a broader and less vaulted glabella that is not inset and has more tectiform flanks. Also, it lacks alar depressions and has a brim that is wider (sag.) and has slightly bigger perforations.
description: Published as part of Johnson, Robert G., 2024, Devonian Harpetidae from the central and eastern Anti-Atlas, Morocco, pp. 1-185 in Zootaxa 5450 (1) on pages 72-73, DOI: 10.11646/zootaxa.5450.1.1, http://zenodo.org/record/11232500