Lioharpes scopulum, Johnson, 2024

Johnson, Robert G., 2024, Devonian Harpetidae from the central and eastern Anti-Atlas, Morocco, Zootaxa 5450 (1), pp. 1-185 : 57-58

Lioharpes scopulum n. sp.

Plate 32E–Q

Diagnosis. Genicranium is narrow (tr.), glabella inset and carinate, axial furrows straight, occipital furrow and occipital ring narrower (sag.) than posterior border (exsag.). CMO on occipital node with four pits arranged in a square, alae longer (tr.) than they are wide (exsag.), no alar depression and genal area without caeca, tubercles or granulation. Inner margin of fringe anterior to glabella not marked by perforations larger than those on genal roll. Brim is concave (sag.), straight laterally and quickly steepening to near vertical on prolongations; brim width ratio under 0.60.

Etymology. Scopulum, Latin for reef, referring to the coralliferous nature of the type locality and horizon.

Material and occurrence. Holotype: NHMUK It 29279, Pl. 32E–L , from coral horizon at the Pragian/Emsian border, Ihandar Formation?, Northern slopes of bou Lachrahl ( Fig. 2B, Map 9, site 2), dorsal exoskeleton, cephalon only . Paratypes: NHMUK It 29280 (1– 3), Pl. 32M–N, O–P, Q , respectively, from type locality and type horizon (site 3), partial dorsal exoskeletons of cephala only .

Description. Cephalon ovoid in dorsal outline, widest at midpoint between eyes and alae. Genicranium width (tr.) just under 90% of length (sag.). Glabella inset, moderately narrow, flanks tectiform, crest carinate and with fine pitting. Axial furrows straight, weakly tapering anteriorly. S1 furrows effaced before curving anteriorly and no muscle insertion furrows at S2, S3 or S4. Muscle insertion areas only visible on uncoated glabella ( Pl. 32E ) as dark patches; S0 oval, S1 tulip-shaped and S2, S3 and S4 subcircular. Occipital furrow deep, narrower (sag.) than posterior border and in dorsal view, straight not bowed. Occipital ring not medially broadened and lower than glabella in lateral view, sloping backwards. Occipital node moderately broad with a CMO of four very fine, symmetrically arranged perforations ( Pl. 32L ). Alae small, width (tr.) 28% of glabella anterior to S0 (sag.), wider (tr.) than long (exsag.) and laterally-directed. Alar furrow shallow, well defined and no alar depression. Posterior border (tr.) 46% of occipital ring (tr.). Preglabellar furrow well-defined, straight in anterior view and width (sag.) around 25% of width (tr.).

Genal area moderately broad (tr.), around 57% of length (exsag.) and with fine pitting. Eye lobes inflated and moderately long (exsag.) at 41% of glabella width at SO. Each eye lobe with three lenses, anterior and posterior reclined ovals, and central lens circular. ( Pl. 32J, K, N ). Anterior lens largest and central lens very small. Eye location ratio is 0.78. Eye ridge poorly-defined and no genal ridge. Inner margin of fringe convex across anterior of genal areas. Boss barely inflated, reaching down to weak girder kink and not attached to glabella. Perforations on genal roll same size as those on brim. Girder moderately wide.

Brim sloping at around 150 (sag.), concave (sag.), straight laterally and moderately wide, being around 32% of cephalic length (sag.). Brim width ratio around 0.60. Standardised brim perforations between 100µm and 150µm in diameter, with no graduation in size across brim. Caeca on genal roll and across brim. External rim stout with fine tubercles on dorsal surface. Length (exsag.) of prolongations 72% of cephalic length (sag.) and genal spine short. In dorsal view, internal rims curving adaxially to continue into genal spine. On prolongations, extension of girder meeting internal rim just under halfway down and brim steepening quickly to near vertical.

Hypostome, thorax and pygidium unknown.

Remarks. Lioharpes scopulum lacks two of the genus’ 8 diagnostic characters shown in Table 5a: the occipital furrow is narrower (sag.) than the posterior border (exsag.) and the width (tr.) of its posterior border is about 46% of the width (tr.) of the occipital ring, wider than the upper diagnostic range of 31% to 40%.

Lioharpes scopulum is similar to L. saredra , which has been found at the same locality ( Pl. 15K–N ), but it has the following differences: widest (tr.) point of the cephalon is posterior to the eye lobes rather than at the eye lobes; glabella is inset, carinate and finely pitted; muscle attachment areas at S2, S3 and S4 are not visible; there is no interalar ridge or alar depression and the axial furrow crosses the junction of the ala and L1; there are 3 eyes lenses per eye tubercle, not two, with the anterior lens being larger than the posterior lens; the course of the fringe inner margin across the anterior of the genal areas is convex not concave, and as it crosses below the preglabellar field, its path is not marked by perforations bigger than those on the main part of the genal roll; the perforations on the genal roll are the same size as those on the brim, not smaller; and the genal prolongations are shorter, some 70% of the cephalic length (sag.), rather than just under 90% in the case of L. saredra .

The small central eye lens is difficult to discern on the holotype. In Pl. 32J (dorsal view), the lens appears to be a gentle dome in shape, but in Pl. 32K (lateral view), the lens appears flat and is defined by a subcircular furrow which is intersected by a smaller subcircular furrow below. In Pl. 32N (dorsal view), the small lens which is from the paratype NHMUK It 29280 (1) is much clearer .

The occipital node, with a CMO with four small pits arranged symmetrically in a square pattern, is similar to that found on Pinnuloharpes hamarlagdadensis (new material, Pl. 44E ), P. aff. haustrum ( Pl. 43J ) and described by McNamara et al. (2009, p. 27, text fig. 4) in Eskoharpes friendi .

Figures

PLATE 15. A-N Lioharpes saredra n. sp. A–C partial dorsal exoskeleton of cephalon from “Odontochile Couche” Boutiskaouine Formation, Emsian, Jbel Oufatene (Fig. 2B, Map 8, site 7), paratype, NHMUK it 29276. A, dorsal and B, lateral view. C, dorsal view of brim perforations. D–J disarticulated dorsal exoskeleton, from the Destombina Horizon, Tazoulait Formation, upper Emsian,Jbel Shebras (Fig. 2B, Map 12, site 1), paratype, NHMUK It 29278. D, dorsal, E, lateral and F, anterior view. Dorsal view of: G, genal area showing internal mould, H, brim perforations, I, pygidium and J external rim. K–N dorsal exoskeleton of cephalon only, from coral at the top of the Pragian, Ihandar Formation, bou Lachrhal (Fig. 2B, Map 9, site 1), paratype, NHMUK It 29277. K, dorsal, L, anterior and M, lateral view. N, dorsal view of brim perforations. Scale bars shown represent 1 cm unless otherwise indicated.

PLATE 32. A–D Maghroharpes terridus n. sp., Ihandar Formation, Pragian, Maharch, dorsal exoskeleton, thorax and pygidium disarticulated, holotype, NHMUK It 29321 (Fig. 2B, Map 9, site 18). A, dorsal, B, lateral and C, posterior view. D, dorsal view of brim perforations. E–Q Lioharpes scopulum n. sp., Ihandar Formation, bou Lachrhal. E–L dorsal exoskeleton of cephalon only, holotype, NHMUK It 29279 (Fig. 2B, Map 9, site 14). E, Dorsal, F, lateral and G, anterior view. H, lateral view of glabella (uncoated), I, dorsal view of brim perforations. J, and K, dorsal and lateral view of eye lobe respectively. L, dorsal view of occipital node. M–Q dorsal exoskeletons of partial cephala only, from type locality and horizon, paratypes, NHMUK It 29280 (1 to 3) (Fig. 2B, Map 9, site 3). M–N NHMUK It 29280 (1). M, dorsal view and N, dorsal view of eye lobe. O–P NHMUK It 29280 (2). O, dorsal view and P, dorsal view of brim perforations. Q, NHMUK It 29280 (3), dorsal view. Scale bars shown represent 1 cm unless otherwise indicated.

PLATE 43. A–B Pinnuloharpes haustrum n. sp., upper Emsian, Hamar Laghdad, dorsal exoskeleton with pygidium enrolled, paratype, NHMUK It 29345 (Fig. 2B, Map 13, site 11). A, anterior and B, lateral view. C– P Pinnuloharpes aff. haustrum, from base of upper Emsian, Hamar Laghdad. C–L dorsal exoskeleton with thorax enrolled, NHMUK It 29347 (1) (Fig. 2B, Map 11, site 7). C, dorsal, D, lateral and E, anterior view. F, dorsal view of brim perforations, G, anterior view of external rim. H, I and J dorsal view of sculpture on dorsal surface of genal area, brim perforations and occipital node, respectively. K, anterior view of perforations on the genal roll and L dorsal view of eye lobe. M–P ventral exoskeleton of cephalon only, NHMUK It 29347 (2), from same site as NHMUK It 29347 (1). M, ventral and N, lateral view. O and P, ventral view of hypostome and external rim, respectively. Scale bars shown represent 1 cm unless otherwise indicated.

PLATE 44. A–M Pinnuloharpes hamarlaghdadensis (Cronier et al. 2018), from Hamar Laghdad, upper Emsian. A–F dorsal exoskeleton with pygidium enrolled, NHMUK It 29337 (Fig. 2B, Map 11, site 1) A, dorsal, B, anterior and C, lateral view. D, dorsal view of brim perforations, E, dorsal view of occipital node and F, lateral view of eye lobe. G–J dorsal exoskeleton of cephalon and 2 pleural segments of thorax, NHMUK It 29338 (Fig. 2B, Map 11, site 2) G, dorsal, H, lateral and I, anterior view. J, dorsal view of brim perforations. K–M dorsal exoskeleton with thorax disarticulated and pygidium absent, NHMUK It 29339 (Fig. 2B, Map 11, site 3) K, dorsal and I, anterior view. L, dorsal view of brim perforations and M, lateral view of distal ends of pleurae. Scale bars shown represent 1 cm unless otherwise indicated.