Pinnuloharpes apteros, Johnson, 2024

Johnson, Robert G., 2024, Devonian Harpetidae from the central and eastern Anti-Atlas, Morocco, Zootaxa 5450 (1), pp. 1-185 : 84-86

Pinnuloharpes apteros n. sp.

Plates 38J–O , 39A–M

Diagnosis. Glabella strongly vaulted and subcylindrical, tapering anteriorly (axial furrows 150 to axis). Preglabellar furrow very shallow, glabella joining with narrow, moderately inflated anterior boss that does not continue down to girder. Alar furrow very shallow and often effaced. Eye lobes slightly inflated, long (exsag.) and reniform. Brim straight, gently sloping and steepening moderately strongly on prolongations. Brim width ratio between 0.7 and 0.8. Perforations over 150 μm on standardised brim. Marginal band with three lateral ridges.

Etymology. Greek for wingless, referring to absence of alae.

Material and occurrence. Holotype: NHMUK It 29358, Pl. 38J–O , from an upper Eifelian horizon, Tamgoute Bulgan ( Fig. 2B, Map 6, site 18), dorsal exoskeleton . Paratype: NHMUK It 29356, Pl. 39A–D , from an upper Eifelian horizon, Ksar Hannabou ( Fig. 2B, Map 6, site 8), dorsal exoskeleton of cephalon only . Paratype: NHMUK It 29359, Pl. 39E–K , from type locality and horizon ( Fig. 2B, Map 6, site 19), dorsal exoskeleton with thorax and pygidium disarticulated . Paratype: NHMUK It 29357, Pl. 39L–M , from “ Harpes Couche ”, upper Eifelian, Ksar Hannabou ( Fig. 2B, Map 6, site 15), dorsal exoskeleton of a partial cephalon .

Other material: Pinnuloharpes aff. apteros : NHMUK It 29379, Pl. 38F –I , from an outcrop 3.8 km west of Ksar Hannabou and 8.3 km S.S.W. of El Jorf, Eifelian ( Fig. 2B, Map 6, site 6), a dorsal exoskeleton of a cephalon.

Description. Cephalon ovoid, widest at mid-point between eye lobes and alae. Genicranium narrow, with length (sag.) 80% of width (tr.). Glabella not inset, narrow, width being just over 60% of length (sag.) of glabella anterior to S0; crest rounded; flanks tectiform; some fine granulation on dorsal surfaces but no pitting; S1 effaced. Axial furrows are convex and converge strongly anteriorly, at an angle to axis of just over 15°. Preglabellar furrow indistinct but straight in anterior view. No preglabellar field. Occipital furrow deep and medially straight, and occipital ring lacks sculptural tubercles. In lateral view, height of occipital ring same as height of glabella anterior to S0. Width (sag.) of both occipital furrow and occipital ring greater than width of posterior border (exsag.). Occipital node small located on anterior edge of occipital ring. Alar furrow effaced and no alar depression. Posterior border moderately short (tr.), being 35% of occipital ring width (tr.).

Genal area moderately broad with no caeca or pitting but some granulation. Eyes large (exsag.) but barely inflated, reniform and set away from inner margin of fringe. Each eye lobe has two lenses. No genal ridge, and eye ridge ill-defined. Course of inner margin of fringe across anterior of genal areas straight. No bigger perforations across anterior boss. Boss barely inflated, not reaching girder but joined to glabella. No girder kink. Genal roll sloping gently anteriorly, moderately steeply laterally. Perforations on genal roll smaller than on brim and becoming progressively smaller away from girder. No larger perforations across boss at inner margin of fringe, and genal roll caeca free. Girder moderately narrow (sag.) and with no kink. Brim straight; sloping (sag.) at just under 150; narrow (sag.) with width (sag.) being 27% of cephalic length (sag.). Standardised brim width ratio just under 0.80. Standardised brim perforation diameter 155µm–180µm, and light caeca across brim. Exterior rim stout with granulation on dorsal surface. Marginal band near vertical, straight and with three ridges but no tubercles. Prolongations long (exsag.), being 90% of cephalic length (sag.). In dorsal view, external and internal rims curve adaxially. In lateral view, internal rim straight, sloping down to end of prolongations where it meets and joins with external rim. Genal spine short. Dorsal surface of internal ring tubercle-free. Extension of girder meets internal rim about 1/3 way down prolongation. Brim steepens to near vertical on prolongations.

Thorax with 24 segments. Axis tapers posteriorly, so that width (tr.) of last axial ring just over 30% of first. Thorax widens posteriorly to 5 th segment, then tapers posteriorly so that inner portion of pleura on last segment 35% of longest pleura. Pleural furrow is narrow and almost effaced. No pitting on pleurae, and on last 11 thoracic segments, outer portion of pleurae slightly offset posteriorly to inner portion. Outer portion turns down, curves anteriorly and distal ends pointed. Outer portion less than vertical anteriorly and becoming less steep on each segment posteriorly from 12 th segment. Pygidium has 3 axial rings and lacks border and tubercles.

A disarticulated pygidium is shown in Pl. 38O , with three axial rings and terminal piece. Interpleural furrows shallow and reach to distal edge of pygidium. Pleural furrows very shallow on first and second pleural bands. Terminal piece short (sag.), wide (tr.) and rounded.

Remarks. Pinnuloharpes apteros has an inner margin of the fringe which is straight across the anterior of the genal areas, not concave. Otherwise, P. apteros has the diagnostic characters of Pinnuloharpes s.s. shown in Table 5c.

Pinnuloharpes apteros is unusual amongst harpetids in having alar furrows that are largely effaced. It is otherwise similar to material presented by Feist in his doctoral thesis (1977, pl. XII, fig. 10–11), in having a relatively short (sag.), strongly vaulted cephalon, no girder kink and a brim covered by fine caeca. This material, however, has a preglabellar furrow and a short preglabellar field. It also has an eye ridge and a rounded dorsal surface to the eye lobe. The dorsal surface of P. apteros’ s eye lobe is straight and sloping adaxially.

P. apteros is similar to P. segaouii but has: a cephalon that is widest (tr.) between eyes and alae rather than at the alae; a narrower genicranium; no furrow at S1 whereas P. segaouii has a shallow S1 furrow; a broader occipital ring; a more robust but narrower (tr.) posterior border; alar furrows that are effaced whereas those of P. segaouii are just discernible; a genal area that is not as broad; eyes lobes that are closer to inner margin of the fringe and no eye ridge; an inner margin of the fringe that has a course across the anterior of the genal area which is straight not concave and across the anterior of the boss that is not marked by a row of large perforations; an anterior boss that does not reach down to the girder; preaxial furrows that converge, perforations on the genal roll that are smaller than those on the brim, not the same size, and which become smaller away from girder; a narrower brim with larger perforations and light caeca across the whole surface; marginal band with top, bottom and medial ridges rather than just a ridge around the top, and internal rims that in dorsal view curve adaxially rather than being sub parallel and in lateral view meet the external rims at the end of the prolongations and not before, as in the case of P. segaouii . Also, P. apteros has a thorax that tapers more posteriorly, and the distal ends of pleura terminate in a point are not rounded.

P. aff. apertos ( Pl. 38F–I ) differs from P. apteros by having: axial furrows that do not converge anteriorly so strongly; an anterior boss that reaches down to the girder; a genal roll that slopes less steeply anteriorly and laterally; a slightly broader (sag.) brim that slopes more steeply, has a convex rather than straight profile and finer brim perforations; a marginal band that is without ridges; much longer prolongations with the internal rims curving adaxially and then abaxially, and external rims straight slanting adaxially rather than curving adaxially; no genal spine and an extension of the girder that meets the internal rim just over 1/5 of the way down compared to 1/ 3 in the case of P. apteros .

Figures

PLATE 38.A–E Pinnuloharpes aff. torquis, dorsal exoskeleton of cephalon only, El Otfal Formation, upper Eifelian, Tamgoute Bulgan (Fig. 2B, Map 6, site 20), NHMUK It 29329. A, dorsal, B, lateral and C, anterior view. D, lateral view of eye lobe (uncoated) and E, dorsal view of brim perforations. F–I Pinnuloharpes aff. apteros, dorsal exoskeleton of cephalon only, El Otfal Formation, upper Eifelian, “Harpes Couche”, Ksar Hannabou (Fig. 2B, Map 6, site 6), NHMUK It 29379. F, dorsal, G, lateral and H, anterior view. I, lateral view of eye lobe. J–O Pinnuloharpes apteros n. sp.,dorsal exoskeleton, El Otfal Formation, upper Eifelian, Tamgoute Bulgan (Fig. 2B, Map 6, site 18), holotype, NHMUK It 29358. J, dorsal, K, anterior and L, lateral view. M, lateral view of pleurae, N, dorsal view of brim perforations and O, posterior view of pygidium. Scale bars shown represent 1 cm unless otherwise indicated.

PLATE 39. A–M Pinnuloharpes apteros n. sp., El Otfal Formation, upper Eifelian. A–D dorsal exoskeleton of cephalon only, paratype, NHMUK It 29356 from Ksar Hannabou (Fig. 2B, Map 6, site 8). A, dorsal, B, anterior and C, lateral view. D, dorsal view of brim perforations. E–K dorsal exoskeleton with thorax and pygidium disarticulated, paratype, NHMUK It 29359, from type locality and horizon (Fig. 2B, Map 6, site 19). E, dorsal, F, anterior and G, lateral view. H, dorsal view of brim perforations, I, lateral view of eye lobe, J, anterior lateral view of rim and marginal band, and K, dorsal view of pleurae close to pygidium. L–M dorsal exoskeleton of a partial cephalon, paratype, NHMUK It 29357, from Ksar Hannabou (Fig. 2B, Map 6, site 15). L, dorsal view and M, dorsal view of brim perforations. Scale bars shown represent 1 cm unless otherwise indicated.