Neobuthus Hirst, 1911

Kovařík, František, Lowe, Graeme, Awale, Ahmed Ibrahim, Elmi, Hassan Sh Abdirahman & Abdi, Ali, 2018, Scorpions of the Horn of Africa (Arachnida, Scorpiones). Part XVII. Revision of Neobuthus, with description of seven new species from Ethiopia, Kenya and Somaliland (Buthidae), Euscorpius 271, pp. 1-82 : 2-4

Neobuthus Hirst, 1911

( Figs. 1–438, Tables 1–5)

Neobuthus Hirst, 1911: 462 ; Kovařík & Lowe, 2012: 1– 25, figs. 1–6, 9–74, 86, 89, 92, 95–96, 100–101 (including complete generic synonymy prior to 2012); Kovařík et al., 2013: 4, 14; Lowe & Kovařík, 2016: 1–46, figs. 1–165, tables 1–5.

DIAGNOSIS. Small buthid scorpions, total length 15–25 mm (males), 22–32 mm (females); carapace strongly trapezoidal, surface granular with only anterior median carinae developed; ventral aspect of cheliceral fixed finger usually with single denticle, but this may be reduced or atrophied ( N. ferrugineus ); tergites with three carinae, of which the lateral pair may be less conspicuous; sternites III– VI with finely micro-denticulate posterior margins, lacking larger non-contiguous denticles; pectines with fulcra, hirsute; metasomal segments I–III with 8–10 carinae, segment V with enlarged lobate dentition on posterior ventrolateral carinae; telson rather bulbous, vesicle steeply inclined posteriorly, aculeus shorter than vesicle; macrosetae on vesicle normal to surface (♂) or oriented in anterior direction (♀); pedipalps short with stout segments, movable finger of pedipalp with 4–6 subrows of primary denticles flanked by mid-row internal and proximal external accessory denticles, 3 denticles just proximal to terminal denticle; movable finger without dense terminal brush of setae on ventral surface; strongly spatulate microsetae not present on termini of fixed and movable fingers; pedipalp finger margins straight, without proximal scalloping or basal lobe and notch; trichobothrial pattern type A, orthobothriotaxic or neobothriotaxic minorante, dorsal trichobothria of femur arranged in β- configuration; trichobothrium d 2 of pedipalp femur present or absent on dorsal surface, d 2 of pedipalp patella present or absent, d 3 of pedipalp patella situated internal to dorsomedian carina, V 2 of chela manus strongly displaced internally relative to V 1 , chela fixed finger with db located in proximal half, proximal to est; tibial spurs present on legs III–IV; sexual dimorphism in setation, granulation and metasomal dentition: pedipalps, legs and metasoma with weaker granulation and long, filiform macrosetae in females, stronger granulation and shorter (often spiniform) macrosetae in males, ventrosubmedian and ventrolateral carinae on segments II–III strongly developed with enlarged dentition in females and regular dentition in males; capsule of hemispermatophore with 4 lobes in typical 3+1 configuration, basal lobe a broad, robust, hook-like process, flagellum well separated from lobes .

HEMISPERMATOPHORE. The hemispermatophores of all examined Neobuthus species exhibit similar morphology. The trunk is long and narrow, becoming broader in its basal half, and terminates apically in a short capsule region. The flagellum is well separated from the sperm hemiduct lobes and consists of a pars recta with laminate expansion on its anterior margin, and a narrow, cylindrical hyaline pars reflecta. The sperm hemiduct of the capsule region is 3-lobed, with large, apically rounded, spatulate posterior lobe attached by thickened suture or carina to concave surface of smaller acuminate median lobe. A small anterior lobe is well separated from the median lobe by a large gap. A robust, hook-like basal lobe with blunt apical profile projects from the convex surface at the base of the median lobe, attached along an oblique axis. The convex surface of the basal lobe is oriented anteriorly, and the concave surface posteriorly towards the flagellum. Intraspecific variation in lobe morphology was as great as interspecific variation, and we did not find systematic differences that could be useful in diagnosis at the species level. Sample sizes compared were (number of individuals, including previous studies): N. amoudensis sp. n. 10, N. awashensis 1, N. cloudsleythompsoni 1, N. erigavoensis sp. n. 4, N. eritreaensis 2, N. factorio sp. n. 3, N. gubanensis sp. n. 5, N. kutcheri 1, N. maidensis sp. n. 1, and N. montanus sp. n. 3. Left and right hemispermatophores in the same individuals did not differ significantly in their morphology. The consistent shape of the basal lobe within Neobuthus supports its use as a higher taxonomic character for differentiating between different buthid genera.

TAXONOMIC REMARKS. Key diagnostic characters for the genus Neobuthus originally proposed by Kovařík & Lowe (2012) were based on 3 species. These characters were subsequently confirmed by Lowe & Kovařík (2016) for 3 additional species. Here, we restudy two of the original species and describe 7 additional species. Our results further support the validity of the diagnostic characters. One key character was the presence of a single enlarged denticle on the ventral aspect of the cheliceral fixed finger. We confirmed that N. amoudensis sp. n., N. erigavoensis sp. n., N. factorio sp. n., N. gubanensis sp. n., and N. montanus sp. n also comply with this character ( Figs. 21, 118, 175, 257, and 393). In N. ferrugineus ( Kraepelin, 1898) , the denticle was smaller and difficult to visualize due to lack of darkening and concealment under microsetae ( Fig. 210). However, UV microscopy of the profile of the ventral surface of the cheliceral fixed finger revealed a distinct tubercle ( Fig. 212) that likely corresponds to a reduced ventral denticle. The difficulty of visualizing this under light microscopy explains why Kraepelin (1903) placed this species in Nanobuthus Pocock, 1895 , which lacks ventral denticles as a diagnostic character ( Pocock, 1895), and furthermore considered it a synonym of N. andersoni Pocock, 1895 . Apparently, Prendini (2004, unpublished, cf. label in Figs. 182–183) concurred with this synonymy. We defer consideration of this issue until we can analyze the type or topotypes of N. andersoni , but if synonymy is upheld then Neobuthus would become a junior synonym of Nanobuthus .

Another key character is the 3+1-lobe configuration of the hemispermatophore capsule region with a strong, hook-like basal lobe. This was confirmed also in our newly described species (see above). The general lobe configuration is consistent with placement of Neobuthus in the ‘Buthus’ group (Fet et al., 2005) that was defined by trichobothrium d 3 of the pedipalp patella being internal to the dorsomedian carina (Lowe et. al., 2018). Other key characters including sternite margin microdenticulation and various features of metasomal carination and setation were also validated.

TERATOLOGY. Among the samples examined, we detected two novel cases of anomalous structural development. In the first case, an adult paratype female of Neobuthus gubanensis sp. n. bore a malformed right pectine that was greatly abbreviated, with only 5 teeth ( Figs. 432–434). The basal-most pectinal tooth had a much reduced sensillar area extending over only the distal third of the tooth, and the distal-most tooth had an unusual proximal annular constriction. Of particular interest was the presence of two hook-like processes on the anterior margin where marginal lamellae are normally positioned. These processes were curved with pointed tips composed of dark, hardened cuticle, resembling telotarsal ungues. Another area of dark, hardened cuticle was expressed along the anterior edge of a single middle lamella exposed in a gap without marginal lamella. A similar case of development of tarsus-like structures in place of normal pectines was recently reported in an immature male of Scorpiops luridus Qi et al., 2005 (family Euscorpiidae ) (Di et al., 2018). That case was interpreted as a homeotic mutation, yielding evidence that scorpion pectines are homologous to telopodites (= distal parts of primitive limbs). Our observation of a similar partial pectine-to-leg transformation in a phylogenetically distant buthid taxon supports the notion that this type of mutation, and inferred homology, is characteristic of Order Scorpiones , rather than being merely a phenomenon unique to Euscorpiidae .

In the second case, an adult male paratype of N. montanus sp. n. exhibited abnormal development of its genital opercula ( Figs. 435–437). Normally, male opercula are slightly overlapped along the midline and freely articulate along their anterolateral attachment margins, allowing them to swing open for spermatophore extrusion. In this case, the sclerites were much more overlapped medially, and the right operculum was also posterolaterally attached and thus unable to articulate. Only a single genital papilla was detected by fluorescence behind this attached sclerite, instead of the normal pair of papillae. Interestingly, intact hemispermatophores were extracted from this male, even though it may have been difficult if not impossible for any spermatophore to be extruded via this mostly occluded genital opening.

SUBORDINATE TAXA. N. amoudensis sp. n., N. awashensis Kovařík & Lowe, 2012 , N. berberensis Hirst, 1911 (type species), N. cloudsleythompsoni Lourenço, 2001 , N. erigavoensis sp. n., N. eritreaensis Lowe & Kovařík, 2016 , N. factorio sp. n., N. ferrugineus ( Kraepelin, 1898) , N. gubanensis sp. n., N. kloppersi sp. n., N. kutcheri Lowe & Kovařík, 2016 , N. maidensis sp. n., N. montanus sp. n., and N. sudanensis Lourenço, 2005 (taxonomic position unclear).