Pinnuloharpes segaouii, Johnson, 2024

Johnson, Robert G., 2024, Devonian Harpetidae from the central and eastern Anti-Atlas, Morocco, Zootaxa 5450 (1), pp. 1-185 : 83-84

Pinnuloharpes segaouii n. sp.

Plate 35A–P

Diagnosis. Genicranium wide, length (sag.) 1/3 width (tr.). Glabella with tectiform flanks, rounded crest and joined to anterior boss. Occipital ring length (sag.) same as posterior border length (exsag.); posterior border wide (tr.), half width of occipital ring (tr.). Alae subtriangular and genal roll sloping gently anteriorly. Brim width ratio just under 0.80; brim gently sloping anteriorly, steepening laterally to over 600 on prolongations. Perforations on brim moderately fine and internal rims are subparallel.

Etymology. For Hmad Segaoui, who assisted in field work in the Anti-Atlas.

Material and occurrence. Holotype: NHMUK It 29351, Pl. 35A–G , from an upper Eifelian horizon, El Otfal Formation, Tarhroat ( Fig. 2B, Map 10, site 4), dorsal exoskeleton partially enrolled . Paratype: NHMUK It 29352, Pl. 35H–K , from horizon 1, Section 2 ( Fig. 7 ), El Otfal Formation, upper Eifelian , Taboumakhloȗf, Jbel Issoumour ( Fig. 2B, Map 7, site 11), dorsal exoskeleton enrolled . Paratype: NHMUK It 29350, Pl. 35L–P , from the main “ Harpes ” horizon, 2 m upslope of the “ Acanthopyge ” horizon, El Otfal Formation?, Eifelian / Givetian boundary, Timerzit ( Fig. 2B, Map 10, site 4), dorsal exoskeleton of incomplete cephalon .

Description. Cephalon is ovoid, widest at alae. Genicranium very broad, width (tr.) 1.40 times length (sag.). Glabella broad (width (tr.) 70% of length (sag.)), not inset and with tectiform flanks and rounded crest. No sculpture or pitting, and S1 short, sloping posteriorly. Axial furrows convex, converging weakly anteriorly. Occipital furrow shallow and medially straight in dorsal view. Occipital ring without sculpture, not medially broadened, same width (sag.) as posterior border (exsag.) and, in lateral view, higher than glabella anterior to S0. Occipital node small and moderately inflated. Alae small (tr.) and subtriangular in shape. Alar furrows shallow and no alar depression. Posterior border wide (tr.), 55% of occipital ring width (tr.). No preglabellar field. Genal area very broad and without caeca or tubercles. Eye lobes oval; barely inflated but large, length (exsag.) 40% of width (tr.) of glabella at S1; and located away from inner margin of fringe. Each lobe has two lenses of equal size. No genal ridge, and eye ridge not well defined. Genal roll sloping gently anteriorly, moderately steeply laterally. Perforations on genal roll same size as those on brim, except for bigger perforations at inner margin of fringe as it crosses anterior boss. No row of larger perforations above girder. In lateral view, inner fringe narrowing very strongly posterolaterally. Brim straight, sloping slightly and moderately wide (sag.), 34% of cephalic length (sag.). Brim width ratio 0.77. Brim perforations moderately fine, with a diameter of just over 100 µm. Exterior rim stout and without sculpture on dorsal surface. Marginal band near vertical, straight and with no ridges or tubercles. Length of prolongations (exsag.) just under 90% of cephalic length (sag.). Internal rims subparallel in dorsal view and lack tubercles on their dorsal surfaces. Genal spines long, over 10% of length of prolongations and following curve of external rim. Extension to girder meeting internal rim about 1/3 of way down prolongation. Whole brim steepens to less than vertical on prolongation.

Thorax with at least 22 segments. Axis not strongly tapering, width (tr.) of last axial ring being 53% of first. Axial rings without tubercles or pits. Thorax widening posteriorly to 5 th segment, thereafter width (tr.) of pleurae reducing posteriorly, particularly towards distal end of thorax. Pleural furrows narrow, almost effaced. Outer portion set at an angle to inner portion, slanting posteriorly before curving anteriorly as it turns down. Distal ends rounded ( Pl. 35E ).

Hypostome and pygidium unknown.

Remarks. Pinnuloharpes segaouii is similar to P. torquis but differs in having: a cephalon that is widest at the alae and not at the midpoint between the alae and the eye lobes; a genicranium that is 15% wider; a furrow at S1 that curves around the top of the muscle insertion area and a very shallow alar furrow, while in P. torquis the S1 furrow is a shallow depression in the axial furrow and the alar furrow is effaced; a broader genal area; eye lobes that are more oval than reniform; an ill-defined eye ridge, which is absent in P. torquis ; a row of larger perforations at the inner margin of the fringe where it crosses the anterior of the boss; perforations on the genal roll that are the same size as those on the brim, whereas those of P. torquis are smaller; a much narrower girder without the central row of large perforations, but with a row of perforations above it that are larger than those on the genal roll immediately above; a wide (sag.) brim, 33% of cephalic length (sag.), and a brim width ratio of 0.76, versus 26% and 0.86, respectively in P. torquis ; no caeca on the brim (very light caeca on brim of P. cf. torqui s); much shorter (exsag.) prolongations in relation to cephalic length (sag.), which are less strongly tapered in lateral view; internal rims subparallel in dorsal view, rather than curving adaxially, and straight not concave in lateral view. Girder extension meets internal rim 1/3 way down the prolongation, not 1/4 as in P. torquis .

Figures

FIGURE 7. Section 2 Jbel Issoumour

PLATE 35. A–P Pinnuloharpes segaouii n. sp., El Otfal Formation, upper Eifelian. A–G dorsal exoskeleton partially enrolled, holotype, NHMUK It 29351, from Taghroute near Timerzit (Fig. 2B, Map 10, site 4). A, dorsal, B, posterior, C, anterior and D, lateral view. E and F, dorsal view of pleurae and brim perforations, respectively. G, lateral view of eye lobe (uncoated). H–K dorsal exoskeleton enrolled, paratype, NHMUK It 29352, the lower “Harpes Couche” (Fig. 7), Jbel Issoumour (Fig. 2B, Map 7, site 11). H, dorsal, I, anterior and J, lateral view. K, dorsal view of brim perforations. L–P dorsal exoskeleton of an incomplete cephalon, paratype, NHMUK It.29350 from the main “Harpes” horizon, 2 m upslope of the “Acanthopyge” horizon, El Otfal Formation? Eifelian/Givetian boundary, Timerzit (Fig. 2B, Map 10, site 1). L, dorsal, M, lateral and N, anterior view. O and P, dorsal view of and brim perforations and impression of ventral surface cuticle on genal area, respectively. Scale bars shown represent 1 cm unless otherwise indicated.