Harpetidae Hawle & Corda, 1847

Johnson, Robert G., 2024, Devonian Harpetidae from the central and eastern Anti-Atlas, Morocco, Zootaxa 5450 (1), pp. 1-185 : 43-44

Family Harpetidae Hawle & Corda, 1847

Genus Harpes Goldfuss, 1839

Type species. Harpes macrocephalus Goldfuss, 1839 , from the Übergangskalk der Eifel (recte Auburgschichten der Crinoidenzone, Devonian), Gerolstein, Eifel, Germany

Emended diagnosis: Cephalon strongly vaulted and ovoid. Preglabellar field narrow (sag.) (20% to 30% of width (tr.)) and posterior border short (tr.) (20% to 30% of width (tr.) of occipital ring). Genal area narrow, width (tr.) under 54% of length (exsag.). Alae large, extending over 60% of way across (tr.) genal area. Eye lobe forms prominent inflated cone or oval extending from edge of axial furrow to near internal margin of fringe. Anterior boss absent or barely inflated and girder without kink. Genal roll and brim free of caeca. Brim slightly concave (sag.), straight laterally, gently to moderately sloping and steepening quickly to near vertical on prolongations. Brim narrowing (tr.) moderately strongly to very strongly posteriorly (brim width ratio <0.68). Extension of girder meeting internal rim one third of the way down prolongation. Thorax up to 31 segments.

Discussion. Harpes has been used as a “catch all” for all species of harpetids which cannot be readily assigned to other genera. Supported by the results of the cladistic study, here the author intends to narrow the concept, distinguishing Harpes from other genera by their prominent eye lobes and alae and their relatively narrow (tr.) genal area. This genus was re-considered by Ebach & McNamara (2002) but their emended diagnosis was in the author’s view overgeneralised and contained inaccuracies, for instance, eyes are not set “anterior to preglabellar furrow”, an inaccuracy which was pointed out by Basse & Müller (2004, p. 75). The author has omitted “cephalon semi-circular to ovate. Brim flat, pitted, rim wide and raised along whole margin” and “genal roll long (sag.), convex and vaulted,” as these descriptions are either inaccurate or apply to many other harpetids. No Harpes brim is flat, many are straight, but all are sloping to some degree.All harpetid species have pitted brims and nearly all have raised rims and genal rolls with a degree of convexity. No species of Harpes has the widest part of its cephalon across (tr.) its posterior border, and therefore their cephala (ignoring the prolongations) cannot be semi-circular.

The holotype of H. macrocephalus is lost and the type locality in the Eifel region is uncertain, although it is thought to be near Gerolstein where H. macrocephalus is most commonly found ( Basse & Müller, 2004). Harpes macrocephalus has been recently refigured by Basse & Müller (2004, taf. 25 & 26), who also figured material of H. macrocephalus ssp. 1 which was found outside the Eifel region, east of the Rhine, near Wetzlar and is of middle Givetian age. A proper comparison of this subspecies with H. macrocephalus requires further material.

It should be pointed out that, while the outline shape of the cephalon of H. macrocephalus is described as an inverted “U” ( Whittington 1950a) (see Basse & Müller 2004, taf. 25, fig. 320), the outer rims on the prolongations are convergent posteriorly and therefore the cephalon can be considered ovoid in shape. Richter (1920) reported (in addition to two eye lenses per eye lobe) a small tubercle on the dorsal surface of the lobe which he believed was not a third eye lens (taf.17, fig. 10). Harpes macrocephalus is the only species of Harpes with such a tubercle. All other species of Harpes have only two lenses per eye lobe and no “tubercle”.

Ebach & McNamara (2002) listed species assigned to Harpes which seem arbitrary in the light of this research. As a result of this revision, the following have been reassigned: H. perradiatus Richter & Richter (1943) , H. transiens Barrande (1872) and H. sp., Alberti, 1969, to Helioharpes Přibyl & Vaněk (1981) , which was considered a junior subjective synonym of Harpes by Ebach & McNamara (2002). Helioharpes has been re-established, albeit with a much-revised diagnosis. Ebach & McNamara (2002, fig. 2F), figured H. perradiatus and a lthough the figure is imperfect, the material shown is certainly not H. perradiatus , but almost certainly Harpes boudibensis n. sp. This clearly renders their coding of characters in their analysis inappropriate. Harpes pruniformis Alberti (1969) and H. socialis Holzapfel (1895) are reassigned to “ Eskoharpes ” s. l.. Harpes sp. ”2” Feist (1977, p. 153), H. rouvillei Frech (1887) , H. polaris Maksimova (1977) and H.hamarlaghdadensis Cronier et al. (2018) , are reassigned to Fritchaspis , Maghroharpes , “ Lioharpes ” s.l. and Pinnuloharpes respectively. Harpes nymageensis Fletcher (1975) from the lower Silurian is reassigned to “ Scotoharpes ” s. l.. However, the material and the photographs illustrating it are of poor quality and it was only possible to complete the character states for 12 of the 111 characters used in the cladistic study. Harpes sp. “3” Feist (1977, p. 155) has been reassigned to Kielania Vaněk (1963) .

Harpes species which were not included in the cladistic study due to lack of reliable information have been assigned pro tem as follows: H. forojuliensis Gortani, 1909 to Bohemoharpes ; H. fornicatus Novák, 1890 and H. pygmeaus Lütke, 1965 to Pinnuloharpes n. gen and Harpes gracilis ( Münster, 1840) , H. koeneni Wedekind, 1914 , H. pyrenaicus ( Barrois,1866) and H. radians Richter, 1963 to Helioharpes .

Apart from any open nomenclature of other species, all Harpes species have been included in the study and are shown together with their interspecies relationships in Figs 9 and 10c . Within the genus there is a separate group of six species including H. boudibensis that is supported by a character state that is a unique unreversed synapomorphy being in lateral view the wave like profile of the internal rim. The range of the Harpes genus is from lower Emsian to upper Eifelian.

Figures

FIGURE 9. Cladogram consensus of 636 trees with a 31 node collapse and each tree L = 1968, Ci = 12 and Ri =48

FIGURE 10a. Lioharpes and Maghroharpes from tree 1 of 60 found using seed 7