Lioharpes galea, Johnson, 2024

Johnson, Robert G., 2024, Devonian Harpetidae from the central and eastern Anti-Atlas, Morocco, Zootaxa 5450 (1), pp. 1-185 : 55-56

Lioharpes galea n. sp.

Plate 10E–K

Diagnosis. Cephalon ovoid, nearly oval, with external and internal rims curving strongly adaxially. Glabella broad, crest rounded with fine granulation and pitting, and axial furrows convex. Alae anterolaterally directed and eye lobes located away from axial furrow. Brim straight to slightly concave in profile, gently sloping and with large brim perforations (diameter around 220 μm on standardised brim). Well-developed caeca on brim and genal roll. Length (exsag.) of genal prolongations over 90% of cephalic length (sag.).

Etymology. Galaea, Latin for helmet. In dorsal view, the cephalon resembles a helmet.

Material and occurrence. Holotype: NHMUK It 29268, Pl. 10E–H , from a coral horizon just above the Kolihapeltis horizon, upper Pragian , Ihandar Formation, Jbel Otfal ( Fig. 2B, Map 9, site 20), a partial dorsal exoskeleton of a cephalon and thorax . Paratype: NHMUK It 29269, Pl. 10I–K , from the type horizon and locality, an articulated dorsal exoskeleton .

Description. Cephalon widest halfway between eye lobes and alae, genicranium moderately narrow, widest at posterior border. Glabella broad, only slightly tapered anteriorly and not carinated or inset. Flanks convex with fine granulation and pitting along crest. L1 inflated, S1 slanting anteriorly, effaced before curving forward near crest. Preglabellar furrow distinct and straight in anterior view. Occipital furrow deep and medially straight (tr.). Occipital ring not medially broadened, same width (sag.) as posterior border (exsag.) and, in lateral view, same height as glabella anterior to S0. Tubercles on occipital ring not prominent but closely packed. Occipital node small, located on anterior slope of occipital ring. Alar furrow anterolaterally directed, small, under 30% of glabella (tr.) at S1 and nearly as wide (tr.) as long (exsag.) at axial furrow. Alar furrow shallow but well defined. Alar depression present and axial furrow partly effaced at junction of ala and L1. Posterior border moderately short (tr.) and preglabellar field wide.

Genal area moderately broad with pits and faint caeca. Genal ridge present, reaching posterolaterally across onto genal roll. Eye lobes oval, long (exsag.) and inflated. Eye location ratio over 80. Anterior eye lens slightly larger than posterior lens and central lens, which sits between and slightly higher than other two lenses and is much the smallest. Anterior and posterior eye lenses oval, central lens subcircular. Eye ridge not well-defined. Inner margin of fringe across anterior of genal area straight and marked by larger perforations across anterior boss. Boss barely inflated and not joined to glabella or reaching girder. No girder kink. Genal roll moderately gently sloping anteriorly, laterally steep and with caeca. Perforations smaller than on brim with a single row of larger perforations above girder. Fringe narrowing strongly posterolaterally and girder moderately narrow.

Brim concave, barely sloping but steepening along proximal edge on prolongations. Brim width (sag.) 32% of cephalic length (sag.) and brim width ratio 0.85. Light caeca across brim and standardised brim perforations of around 220µm; larger perforations along distal and proximal edges of brim. External rim stout and marginal band near vertical with straight profile. Rim and marginal band free of tubercles. Length (exsag.) of prolongations around 90% of cephalic length (sag.), not strongly tapered in lateral view. Internal rim gently concave as it slopes down to short genal spine, which follows curve of external rim. Internal rim with row of large perforations below and sparse fine tubercles on dorsal surface. In dorsal view, internal and external rims curve adaxially.

Thorax with at least 23 segments. Width (tr.) of last axial ring around 35% of first. Tubercles on axial rings. Inner portion of pleurae increasing in length (tr.) to 5 th segment, before shortening (tr.) until last segment, which is around 40% of 5 th segment. Outer portion of pleurae very short, barely downturned, straight, slanting slightly posteriorly from fulcrum. Distal ends rounded except on first three segments, where they are more pointed.

Hypostome and pygidium unknown.

Remarks. Lioharpes galea differs from L. venulosus ( Hawle & Corda, 1847) Pls 10A–D, 54A–D in having the widest (tr.) point of the cephalon at alae rather than at the midpoint between the alae and eye lobes. The glabella is 15% narrower (tr.) and has a crest that is rounded, not carinate. The alae reach less than two thirds the way across the genal area and are anterolaterally directed, whereas those of L. venulosus reach 75% of the way across and are laterally directed. Standardised brim perforations are larger in L. galea , having a 55% greater diameter. L. galea’s genal prolongations are longer, having a length (exsag.) of around 90% of cephalic length (sag.), compared with 66% to 75% in L. venulosus , and L. galea’s external and internal rims are more strongly curved adaxially. On the thorax, there are tubercles on the axial rings and pleural furrows are broad and shallow, rather than narrow and deep ( Prantl and Přibyl,1954, p.138, para 2) as is the case in L. venulosus .

Of all the Lioharpes species, L. galea , is the most like those of the genus Maghroharpes and in particular, M. oufatenensis . It differs, however, in having: a more ovoid cephalon; a slightly narrower genicranium; a rounded crest to the glabella; axial furrows which do not converge as strongly, are not as convex and do not cross the junction of alae with L1; wider occipital furrow and a slightly narrower occipital ring; genal area with light caeca; alae anterolaterally directed; eye lobes less inflated and with three eye lenses rather than two; genal ridge and well-defined eye ridge present; course of inner margin of fringe across anterior of genal area straight rather than mildly convex; anterior boss more inflated; genal roll with caeca and less steeply-sloping and narrower girder than that of M. oufatenensis . Also, M. oufatenensis has bigger standardised brim perforations; more pronounced caeca right across brim and on genal roll; marginal band straight, not concave; and longer prolongations.

Lioharpes venulosus caillaudi ( Pillet 1972) from the quarry of Ferronnière, Erbray, Loire-Atlantique, France has similar adaxially-curved external and internal rims as L. galea , but it has more in common with L. venulosus venulosus .

Figures

PLATE 10. A–D Lioharpes venulosa, from the Natural History Museum London collection, NHMUK In 4180. A, dorsal, B, lateral and C, anterior view. D, dorsal view of brim perforations. E–K Lioharpes galea n. sp., from coral in an upper Pragian horizon, Ihandar formation, Jbel Otfal (Fig. 2B, Map 9, site 10). E–H partial dorsal exoskeleton, holotype, NHMUK It 29268, E, dorsal, F, lateral and G, anterior view. H, dorsal view of brim perforation. I–K dorsal exoskeleton, paratype, NHMUK It 29269, from type locality (site 11), I, dorsal, J, anterior and K, lateral view. Scale bars shown represent 1 cm unless otherwise indicated.

PLATE 54. A–D Lioharpes venulosus (Hawle & Corda, 1847); type locality Upper Koněprusy Limestones, (Pragian) Koněprusy, Czech Republic, a dorsal exoskeleton of a partial cephalon, Museum of Natural History, Prague L12545. A dorsal view, B lateral view, C anterior view and D dorsal view of brim perforations. E–H Bohemoharpes buphthalmus (Bouček, 1935). Type locality the horizon with Ananaspis fecunda (Ludlow stage), Dlouhá hora near Beroun, Czech Republic, a dorsal exoskeleton of a partial cephalon, Museum of Natural History, Prague L17145. E, dorsal view, F lateral view, G anterior view and H dorsal view of brim perforations. I–L Bohemoharpes naumanni (Barrande 1852); type horizon and zone Cyrtograptus lundgreni zone (Upper Wenlock) Lodenice near Beroun, Czech Republic; dorsal exoskeleton of a partial cephalon, Museum of Natural History, Prague, lectotype (subsequent designation, Prantl and Přibyl, 1954) L6127, IT 48. I dorsal view, J anterior view, K lateral view and L dorsal view of brim perforations. This specimen was illustrated by Prantl and Přibyl,1954 pl. iv fig. 1 and Ebach and McNamara, 2002 Fig 2A. Scale bars shown represent 1 cm unless otherwise indicated.