Barbaracurus gen. n.

(Figures 1–10, 24–28, 32–36, 50–254, 261–265, Tables 1–2)

http://zoobank.org/urn:lsid:zoobank.org:act:75EF2A 5A-6CF8-4F3B-94AB-3374C2902E6C

Babycurus: Kraepelin, 1913: 179–183 (in part); Fet & Lowe, 2000: 76–80 (in part); Kovařík, 2000: 244– 245, 255–256, 260–262, figs. 10, 13, 21–22, 26, 38– 40, tables 1–3 (in part); Kovařík, 2009: 30 (in part).

TYPE SPECIES. Babycurus sofomarensis Kovařík, Lowe, Seiter, Plíšková et Šťáhlavský, 2015 .

ETYMOLOGY. The genus-group name is a patronym honoring Dr. Barbara York Main for her lifelong contributions to arachnology, especially the systematics and natural history of Australian mygalomorph spiders, and also to many other topics in ecology, biogeography, evolution and conservation.

DIAGNOSIS. Small to medium buthids, adults 22–47 mm. Carapace granular, lacking distinct carinae, flat, subrectangular with concave anterior margin. Median eyes on low ocular tubercle in anterior half of carapace; usually with 4, or sometimes 5 pairs of lateral eyes (3 major ocelli, 1–2 minor ocelli). Anterior, central and posterior median furrows distinct, connected by median groove running over ocular tubercle. Sternum type 1, triangular in shape. Tergites I –VI granular, with single median carina which may be obsolete on I–II, tergite VII with 5 carinae. Metasoma elongate, segment I with 10 carinae, II–IV with 8 carinae, lacking lateral median carina. Metasoma V convex, sometimes dilated, carinae present or obsolete. Telson ellipsoidal, pyriform or slightly bulbous, with distinct subaculear tooth. Pectines with fulcra. Hemispermatophore capsule with 2-lobed sperm hemiduct and a long, carinate or scoop-like basal lobe. Chelicerae with typical buthid dentition: movable finger dorsal margin with large subdistal and medial denticles and two smaller basal denticles, ventral margin with two large denticles, dorsal distal tine slightly shorter than ventral counterpart; fixed finger with subdistal denticle, and median and basal denticles formed as a bicusp, ventral surface armed with two small denticles (Figs. 252–254). Pedipalps orthobothriotaxic, type Aβ, femur trichobothrium d 2 internal, patella d 3 external to dorsomedian carina, chela db in distal half of fixed finger. Chela manus smooth, with carinae reduced or obsolete, dentate margins of chela movable finger armed with 6–7 non-imbricated, almost linear or contiguous rows of denticulate granules, each row terminated proximally by an enlarged granule flanked by adjacent single internal and external accessory granules. Most proximal granule row without internal accessory denticle, and either with (species from Horn of Africa and Arabian Peninsula) or without (species from Cameroon and Nigeria) a single isolated external accessory granule midway along its length. Pedipalp chelae sexually dimorphic, males typically with manus dilated and fingers proximally undulate on dentate margins, denticles of proximal granule rows bicuspid. Tibial spurs absent on leg III, present on leg IV, tibia and tarsus III–IV without bristle combs, ventral surfaces of tarsi equipped with two rows of setae, ungues stout.

SUBORDINATE TAXA. B. exquisitus (Lowe, 2000) comb. n. (Oman), B. prudenti (Lourenço, 2013) comb. n. (Cameroon), B. sofomarensis (Kovařík et al., 2015) comb. n. (Ethiopia), B. somalicus (Hirst, 1907) comb. n. (Somaliland), B. subpunctatus (Borelli, 1925) comb. n. (Ethiopia, Somalia), B. ugartei (Kovařík, 2000) comb. n. (Nigeria), B. winklerorum sp. n. (Oman), B. yemenensis sp. n. (Yemen), B. zambonellii (Borelli, 1902) comb. n. (Eritrea).

CYTOGENETICS. The karyotype analyses of three species Barbaracurus sofomarensis comb. n. (2n=22) (Kovařík et al., 2015), B. zambonelli comb. n. (2n=26) (Figs. 261, 262) and B. somalicus comb. n. (2n=36) (Figs. 263, 264) show considerable interspecific variability of the diploid chromosomal numbers within this genus. The chromosomes have holocentric organization which is the typical feature of the family Buthidae (Schneider et al., 2009a) . Males display achiasmatic meisois that is characteristic to the whole order Scorpiones (Schneider et al., 2009b) .

AFFINITIES. Seven of the species in this genus were previously included in Babycurus sensu lato . Here we transfer them to a new genus and describe two additional species in that genus. Barbaracurus gen. n. is a rather morphologically uniform assemblage of species that is distributed mainly in the Horn of Africa and the Arabian Peninsula (Fig. 265). It is differentiated from Babycurus primarily by its pedipalp finger dentition. In Barbaracurus gen. n., the pedipalp chela movable finger is armed with a nearly linear series of 6–7 non-imbricated rows of granules. Each row is terminated proximally by two contiguous enlarged granules, i.e., 1 enlarged primary + 1 external accessory granule, and distally by a single non-contiguous enlarged granule (internal accessory granule) (Fig. 10). The most proximal granule row is not terminated proximally by enlarged granules. However, a single enlarged external accessory granule is present midway along that row in species from Horn of Africa and Arabia (Figs. 2–9), and is absent in West African species, Barbaracurus prudenti (Lourenço, 2013) comb. n. from Cameroon and B. ugartei (Kovařík, 2000) comb. n. from Nigeria (e.g., Fig. 1). The proximal row is longer than other granule rows and may have a small gap adjacent to the external accessory granule, suggesting either a fusion or splitting of rows. Babycurus sensu stricto includes species distributed from the southern part of Ethiopia and Somalia, to Angola and West Africa (Fig. 265, and fig. 1 in Prendini, 2004: 245). The pedipalp chela movable finger is armed with a series of 6–9 slightly oblique, imbricated rows of granules, with successive rows overlapping by ≥ 2 granules. Typically, each row is terminated proximally by three more or less contiguous enlarged granules, i.e., 1 enlarged primary + 2 external accessory granules (except for B. gigas which has only has 1 enlarged primary + 1 external accessory granule), and distally by a single noncontiguous enlarged granule (internal accessory granule) (Fig. 11). One or rarely two enlarged external accessory granules are present midway along the proximal row.

The presence of imbricated granule rows and the number of enlarged external accessory granules per row, are potentially informative characters for discriminating buthid genera. For example, imbricated rows differentiate Ananteroides from Ananteris (Lourenço, 1985), and Heteroctenus from Rhopalurus (Esposito et al., 2017) . Among 89 buthid genera with chela dentition arranged in discrete granule rows, imbrication (defined here as ≥ 2 granules overlap of sequential rows) is uncommon, occurring in only 11/89 genera: Ananteroides, Babycurus sensu stricto, Buthoscorpio, Centruroides, Egyptobuthus, Grosphus, Heteroctenus, Mesotityus, Odonturus, Tityus and Zabius (published data and examination of materials in our collections). To the extent of available data, this character was fairly consistent among species within the same genus, with a few exceptions. Its incidence correlated with the major suprageneric groups derived from cladistic analysis of trichobothriotaxy (Fet et al., 2005). The largest number of imbricated genera belong to the neotropical Tityus group (5/11, with 14 genera in the group) and the Afrotropical/ Madagascar Uroplectes group (3/11, with 17 genera in the group). In the Isometrus group, only Babycurus and Odonturus have imbricated rows among the 8 genera (including Barbaracurus gen. n.). Imbrication increases the number of dentate granules that can be packed onto the margins of pedipalp fingers, which is expected to enhance the ability of chelae to securely grasp struggling prey items. This biomechanical advantage could have propelled independent evolution of imbrication as adaptive specializations in different scorpion lineages. Interestingly, imbricated rows were conspicuously absent from the large and successful Palaearctic Buthus group (40 genera, excluding Microbuthus, Femtobuthus and Picobuthus, which lack well defined granule rows).

We also compared numbers of proximal external accessory granules per row across 89 buthid genera. Two external granules were present in 16/88 genera: Microananteris, Babycurus sensu stricto, Charmus, Thaicharmus, Butheoloides, Buthoscorpio, Egyptobuthus, Grosphus, Microcharmus, Neogrosphus, Neoprotobuthus, Odonturus, Pseudolychas, Tityobuthus, Troglotityobuthus and Uroplectes . Most cases belong to the Uroplectes group, and none to the Buthus and Tityus groups. Pseudochactidae is hypothesized to be a basal scorpion family and sister of Buthidae (Prendini et al., 2006; Sharma et al., 2015), so it can serve as an outgroup to polarize buthid characters. All pseudochactids exhibit simple, non-imbricated linear series of granules with a single external accessory granule. Therefore, imbricated rows and dual external accessory granules may both be derived characters in buthids, implying that Barbaracurus gen. n. is the more plesiomorphic genus relative to Babycurus . Although Babycurus has both imbricated rows and dual external granules, it is one of only five genera in which these two characters occur together. Indeed, the two characters were poorly associated across genera (e.g. Jaccard index 0.2272, Dice coefficient 0.3704), indicating that they are neither ontogenetically nor functionally linked.

Another diagnostic character that we propose for separating Barbaracurus gen. n. from Babycurus is the form of the hemispermatophore basal lobe. Both genera have quite similar two-lobed sperm hemiducts, with a narrow anterior lobe and a broad, carinated posterior lobe separated by a key hole-like aperture at their base where sperm exits (Figs. 24–31). In contrast, the basal lobes show much greater variation. Although we were not able to conduct an exhaustive survey of all known species, comparison of basal lobe structures of 5/9 species of Barbaracurus gen. n. (Figs. 32–36) and 3/13 species of Babycurus (Figs. 37–39) revealed a distinct trend. In Barbaracurus winklerorum sp. n., B. exquisitus and B. sofomarensis, the basal lobe is a moderately to strongly projecting, extensive, scoop-like lamina, oriented along an oblique transverse axis, with its distal end at the anterior base of the posterior lobe (figs. 32– 34). In B. somalicus and B. zambonellii, the lobe is reduced to an oblique, transverse carina that may be weaker posteriorly (Figs. 35–36). In the three species of Babycurus examined, basal lobes are further atrophied to a short, weak carina near the anterior base of the posterior lobe (Figs. 37–39). Since strongly developed basal lobes are present in most buthid genera, we hypothesize that the projecting scoop-like basal lobe of the 3 Barbaracurus species is plesiomorphic, and that the progressively reduced forms in other species represent derived states. This further argues for the primitive status of Barbaracurus gen. n. compared to Babycurus . We provisionally included this character in our generic diagnoses, pending a more complete analysis of the hemispermatophores of other species. As Barbaracurus gen. n. appears so far to be defined by plesiomorphic characters, we cannot yet infer anything about its affinities with respect to other genera in the Isometrus group.

Key to species of Barbaracurus gen. n.

1 Pedipalp movable finger without an external accessory granule midway along most proximal granule row (Fig. 1) ..............………………………………............. 2 – Pedipalp movable finger with an external accessory granule midway along most proximal granule row (Figs. 2–9) ................................................................................ 3

2 Base color uniformly yellow or orange, without any darker markings; sternite VII with very weak carination ..................…………........ B. prudenti (Lourenço, 2013) – Base color yellow with brown spots on carapace, dark stripes on tergites, dark pedipalp patella and metasoma V; sternite VII with 4 well developed carinae ...........………........................ B. ugartei (Kovařík, 2000)

3 Pedipalp movable finger with 6 rows of granules (Figs. 2–4) .......……...................................................... 4 – Pedipalp movable finger with 7 rows of granules (Figs. 5–9) .......……...................................................... 6

4 Pedipalp chela with narrower manus, chela length/ width ratio 4.3–5.1, finger margins weakly undulate at base, not leaving gap when closed (figs. 81, 84, 86 in Kovařík et al., 2015) .... B. subpunctatus (Borelli, 1925) – Pedipalp chela with broader manus, chela length/ width ratio 3.4–4.2, finger margins strongly undulate at base, leaving wide gap when closed ....………….......... 5

5 Telson vesicle pyriform in lateral profile, deeper anteriorly (Figs. 83–84); telson length/ depth ratio 2.75– 2.89; pedipalp movable finger of female very weakly undulate at base (Fig. 57) ..... B. somalicus (Hirst, 1907) – Telson vesicle symmetric in lateral profile (figs. 76– 77 in Kovařík et al., 2015); telson length/ depth ratio 2.60–2.73; pedipalp movable finger of female moderately undulate at base (Fig. 53) ..………......................... ……………….... B. sofomarensis (Kovařík et al., 2015)

6 Pedipalp chela with broader manus (Figs. 58, 60), chela length/ width ratio 4.28 (♀), 3.42 (♂); telson more bulbous (Figs. 88–89), length/depth ratio 2.27–2.37 (♀, ♂); distributed in Africa (Fig. 265) …………………… ................……................. B. zambonellii (Borelli, 1902) – Pedipalp chela with narrower manus (Figs. 62, 64, 66, 68, 210, 212), chela length/ width ratio 4.73–6.12 (♀, ♂); telson ellipsoidal or pyriform (Figs. 82, 86–87), length/depth ratio 2.63–2.89 (♀); distributed in Arabia (Fig. 265) ..……………................................................. 7

7 Telson more slender (Figs. 81–82), length/depth ratio 2.89 (♀), 2.70 (♂); found in Al Hajar mountains of northern Oman (Fig. 265) .... B. exquisitus (Lowe, 2000) – Telson less slender (Figs. 85–87), length/depth ratio 2.63–2.72 (♀); not found in northern Oman ………..... 8

8 Larger size, 40–42 mm (♀); less slender metasoma, metasoma V length/width ratio 2.30–2.46 (♀) …..…… ........................................................ B. yemenensis sp. n. – Smaller size, 30–34 mm (♀), 25–29 mm (♂); more slender metasoma, metasoma V length/width ratio 2.56– 2.58 (♀) ....……........................... B. winklerorum sp. n.