Fetilinia, Lowe & Kovařík, 2020

Lowe, Graeme & Kovařík, František, 2020, Fetilinia dentator gen. et sp. n. from Pakistan (Scorpiones: Buthidae), Euscorpius 328, pp. 1-10 : 1-4

Fetilinia gen. n.

( Figures 1–31 , Table 1 )

http: //zoobank. org/urn: lsid: zoobank. org: act: 4AC13359- 2795-4F1B-A8A3-488CA834199D

TYPE SPECIES. Fetilinia dentator sp. n .

ETYMOLOGY. The generic epithet Fetilinia (masculine; constructed to rhyme with Kraepelinia , a similar genus) is a patronym honoring Victor Fet ( USA) in recognition of his many important contributions to the knowledge of scorpions and his generous support of many scorpiologists. Kraepelinia is a very special genus for VF who published its first record from Turkmenistan where he started his scorpiological career ( Fet, 1984). At the time, the only known specimen of K. palpator ( Birula, 1903) from Turkmenistan was collected in 1972 by Yuri Gorelov (1933–2018), an outstanding naturalist, whose life and work in Central Asia (Badghyz Natural Reserve) has been an inspiration and role model for many young Russian zoologists, including VF.

DIAGNOSIS.Adult size small, total length of subadult male 22 mm. Carapace trapezoidal, densely granulate, without carinae, anterior margin almost straight; median eyes large, ocular tubercle raised; five pairs of lateral eyes present, two reduced in size. Sternum type 1, relatively small, and triangular to subpentagonal in shape; posterior depression very large and deep. Pectines large, with 23–23 teeth in subadult male and 19–19 teeth in juvenile female; fulcra present. Tergites I–VI tricarinate, all tergites densely granulate. Sternites with slit-like spiracles; sternite V without a well-defined smooth patch; sternite VII with weak carinae. Metasomal segments relatively short and stout, nearly uniform in width, with carination well developed; metasoma I–III with 8–10 carinae; metasoma II–III with enlarged dentition on ventrolateral and ventromedian carinae; metasoma V with irregular, enlarged lobate dentition on ventrolateral carinae; posterior margins of tergite VII and metasoma I–III with fine fringes of microsetae. Telson with elongate vesicle, aculeus stout, about same length as vesicle, subaculear tubercle absent. Cheliceral dentition follows typical buthid pattern (Vachon, 1963), fiXed finger with two denticles on ventral surface. Pedipalps slender, chelae narrower than patella; trichobothrial pattern neobothriotaXic type C, femur with trichobothrium d 2 absent, d 1 - d 3 - d 4 arranged in b- configuration (non-refleX angle opening internally), patella d 3 located between dorsomedian and dorsointernal carinae, chela manus Eb 1 - Eb 2 - Eb 3 in δ-configuration (non-refleX angle opening distally), V 1 - V 2 aXis slightly inclined internally, eb on distal manus (not fiXed finger), fiXed finger with db situated near base of finger and distal to est, dt at mid-finger and level with et; dentate margins of pedipalp fingers straight, without lobe/ notch combination, equipped with 8 rows of median denticles arranged nearly linearly, non-imbricated, each flanked by a single eXternal and internal accessory granule; 5 subterminal granules. Legs I– III with tibia and tarsi short, curved, flat, with setation modified into bristlecombs on basitarsi only, telotarsi with two rows of long setae on ventral surface; tibial spurs moderate, tarsal spurs well-developed.

AFFINITIES. Fetilinia gen. n. belongs to the Palaearctic ‘ Buthus ’ group of Fet et al., 2005, according to the following characters: trichobothrial pattern typeA-β; patella trichobothrium d 3 internal to dorsomedian carina, manus Eb 1 - Eb 2 - Eb 3 in δ configuration; tibial spurs present on legs III–IV; pedipalp chela finger median denticle rows non-imbricated; and posterior margins of tergite VII & metasoma I–III bearing fringes of microsetae. Within this group, it is similar to another small monotypic genus, Kraepelinia Vachon, 1974 , which also has: enlarged dentition on ventrolateral and ventromedian carinae of metasoma II–III; irregular, enlarged lobate dentition on ventrolateral carinae of metasoma V; and trichobothrium eb located on distal manus. However, Kraepelinia differs from Fetilinia gen. n. in several other characters: thickened pedipalp fingers that are atypical for buthids; smooth carapace and tergites; metasoma V with large, lobate denticles on ventral surface; telson bulbous and granulate. Fetilinia gen. n. is also similar to five other small ‘ Buthus ’ group genera: Butheolus Simon, 1882 , Orthochirus Karsch, 1891 , Baloorthochirus KovařÍk, 1996 , Orthochiroides KovařÍk, 1998 , and Xenobuthus Lowe, 2018 . These display a similar habitus, with a trapezoidal carapace and small, short pedipalps. Orthochirus and Orthochiroides have telson shapes quite similar to that of Fetilinia gen. n., but they differ in having metasomal segments IV–V dilated and punctate. Butheolus , Xenobuthus and Orthochiroides differ in having bulbous telsons.All five of these genera further differ in lacking enlarged or lobate metasomal dentition. It is possible that Fetilinia gen. n. is phylogenetically associated with this ‘orthochiroid’ compleX, but has evolved its own specialized metasomal structure. The pattern of enlarged metasomal dentition in Kraepelinia and Fetilinia gen. n. also occurs in several other ‘ Buthus ’ group genera: Buthus Leach, 1815 , Femtobuthus Lowe, 2010 , Odontobuthus Vachon, 1950 , Pantobuthus Lourenço & Duhem, 2009 , and Trypanothacus Lowe, KovařÍk, Stockmann & Šťáhlavský, 2019 , and seems to be an adaptation of burrowing scorpions ( Lowe et al., 2019).

REMARKS. We based Fetilinia gen. n. on two type specimens, an immature (subadult) male and a juvenile female. Immaturity of the male is evidenced by a laterally swollen mesosoma in a well fed individual, a condition typical of immatures of many other scorpions that we have reared. The characters supporting an affinity with the ‘orthochiroid’ compleX of small scorpions (most ca. 25–40 mm), imply that the adult of Fetilinia gen. n. is also likely to be small in size. The size, strongly granulated integument and pectinal tooth count of the male are consistent with a late instar subadult, one ecdysis before maturity. Even if it were an earlier instar, the characters of trapezoidal carapace and small, short pedipalps are also partially present in early juveniles of ‘orthochiroid’ compleX scorpions. However, caution is certainly advisable when diagnosing a new genus from immature specimens. We therefore considered the alternative interpretation, that the type specimens represent earlier instars of a larger scorpion belonging to an already eXisting genus in the ‘ Buthus ’ group. A conspicuously dentate metasoma is usually present in early instars of species that eXhibit this character in adults. This narrows the list of likely alternative taXa known from this geographic region to four genera: Kraepelinia , Buthus , Mesobuthus or Pantobuthus . Could Fetilinia gen. n. be an early instar juvenile of one of those genera? The slender pedipalps and elongate telson vesicle of Fetilinia gen. n. are quite different from the robust pedipalps and bulbous telson typical of those four genera. However, these structures can often be quite tenuous in early instars, and later develop to become robust in adults. Kraepelinia palpator is a relatively small scorpion, with adult carapace length ca. 4 mm ( Birula, 1903; Lourenço & Leguin, 2010), which would predict an adult body length of ca. 35 mm. We studied a subadult male Kraepelinia with carapace length 2.9 mm and body length 24 mm, similar in size to the subadult male of Fetilinia gen. n. ( Figs. 30–35 ). The thickened pedipalp fingers and bulbous telson that are unique diagnostic characters of Kraepelinia are already strongly eXpressed in the subadult, showing that Fetilinia gen. n. is not a juvenile of this genus. The other genera in question ( Buthus , Mesobuthus , Pantobuthus ) possess a subrectangular carapace, a shape that differs markedly from the strongly trapezoidal carapace of Fetilinia gen. n. An ontogenetic change from trapezoidal in juveniles to subrectangular in adults is implausible, being the reverse of the predicted polarity of such transformations (i.e., from primitive to derived). Another argument against Fetilinia gen. n. being a juvenile of the other genera stems from their differing trichobothriotaXy, which would violate the established rule that trichobothrial patterns are nearly always conserved ontogenetically ( Vachon, 1974). In Pantobuthus , and most Buthus and Mesobuthus , fiXed finger trichobothrium db is located distal to et, whereas it is level with or proXimal to dt in Fetilinia gen. n. Distal translocation of db is typically associated with stretching and elongation of chela fingers, a trend that opposes the hypothetical ontogenetic transformation of slender fingers in Fetilinia gen. n. to short robust fingers in the other genera. Furthermore, Fetilinia gen. n. is neobothriotaXic, with femur d 2 absent, in contrast to the other genera which are orthobothriotaXic. In scorpions, there is only one documented precedent in which reductive neobothriotaXy in juveniles transforms into orthobothriotaXy in adults. In many, if not all buthids, femoral trichobothrium i 2 is absent in the second instar (first nymph), and only appears in the third and later instars ( Armas, 1986: 22; Lourenço, 1979: 100; Stockmann, 1979: 408; Vachon, 1974: 873; R. Teruel, personal communication). However, similar abrupt early developmental changes have not been reported for buthid petite trichobothria including femur d 2, whose presence or absence is normally consistent across instars. The size and well developed carination and granulation of the holotype male Fetilinia gen. n. indicates that it is not a second instar nymph, and it also has femur i 2 already eXpressed ( Fig. 21 ). In summary, available evidence supports our hypothesis that Fetilinia gen. n. is a new genus that does not fit into any of the eXisting ‘ Buthus ’ group genera.

DISTRIBUTION. Known only from the type locality in northern Pakistan. The collection site lies at the edge of the Kohat Plateau, northeast of the Bannu Basin, an intermontane depression in the tectonically active orogenic belt at the western end of the Himalayas. The local substrate consists of Quaternary alluvial fan deposits produced by erosion of surrounding high mountain ranges ( Abir et al., 2017).

Figures

Figures 1–2. Fetilinia dentator gen. et sp. n., subadult male holotype in dorsal (1) and ventral (2) views. Scale bar: 10 mm.

Figures 3–9. Fetilinia dentator gen. et sp. n., subadult male holotype, metasoma IV–V and telson ventral view (3), metasoma and telson dorsal (4, 7), ventral (5, 8), and lateral (6) views, metasoma V and telson lateral view (9). Figures 3–5 are under UV light. Scale bar: 10 mm (4–8).

Figures 10–23: Fetilinia dentator gen. et sp. n., subadult male holotype. Figures 10–12. Carapace and tergites (10) and sternopectinal area and sternites (11–12) Figures 13–23. Pedipalp segments, chela dorsal (14), eXternal (15), ventral (16) views, patella dorsal (17), dorsoeXternal (18), and ventral (19) views, femur and trochanter dorsoeXternal (20), internal (21), and ventral (22) views, movable (13) and fiXed (23) finger dentition. Trichobothrial pattern is indicated by white circles in Figures 15–18 and 20–21. Figures 10–11 under UV light.

Figures 24–29: Fetilinia dentator gen. et sp. n., subadult male holotype. Figures 24–25. Chelicerae ventral (24) and chelicerae dorsal with anterior part of carapace with median and lateral eyes (25). Figures 26–29. Left legs I–IV, retrolateral aspect (respectively).

Figures 30–31. Fetilinia dentator gen. et sp. n., subadult male holotype in dorsal (30) and ventral (31) views, under UV light.

Figures 32–35: Kraepelinia palpator (Birula, 1903), subadult male habitus in dorsal (32, 34) and ventral (33, 35) views, under white light (32–33) under UV light (34–35).Turkmenistan, Badghyz, Eroilanduz, 35°42'04"N 61°48'53"E, el. 348 m, 7.IV.2002,leg.A.Gromov, GLPC.Scale bar:4 mm.