Orobothriurus alticola ( Pocock 1899 )

Ojanguren-Affilastro, Andrés Alejandro, Campón, Florencia Fernández, Silnik, Susana Lagos & Mattoni, Camilo Iván, 2009, The genus Orobothriurus Maury in central Argentina with description of a new species from El Nevado mountain chain in Mendoza Province (Scorpiones: Bothriuridae), Zootaxa 2209, pp. 28-42 : 35-40

Orobothriurus alticola ( Pocock 1899)

Figs. 2 , 18–19 , 25–35 , Table 2

Bothriurus alticola Pocock 1899: 357 –358, Fig. 1 . Lowe & Fet 2000 (Complete syonymic list until 1998). Acosta 2002: 176, 177; Acosta 2005: 1, 2, 8, 9 12. Acosta & Ochoa 2000: 135, 136, 143; Acosta & Ochoa 2001: 203 –205, 208, 209. Ojanguren-Affilastro 2005: 176, 178, 179, 180, 220, 241.

Type material. Syntypes: ARGENTINA, Mendoza Province, Puente del Inca, 32º49’9.15”S, 69º55’1.82”W, 2721 m a.s.l., 1 male, 1 female ( BMNH).

New synonym: Cercophonius brachycentrus bivittatus Thorell 1877: 183 . Acosta 2005 (Complete list of synonyms until III/2005); Acosta 2006: 20–21. Ojanguren-Affilastro 2005: 181–183, 220, 241. ICZN 2008: 69–70.

Type material. Holotype: ARGENTINA, San Juan, juvenile ( NRS).

Additional material: ARGENTINA, San Juan Province, Cerro El Tontal, path to radio anthem, 31º31’24.7’’S, 69º12’23.3’’W, 3600 m a.s.l., A. A. Ojanguren-Affilastro, L. Compagnucci & L. Piacentini coll., 25/I/2006, 8 males, 4 females, 9 juveniles (MACN-Ar); between Paso de Agua Negra and Aduana, Vega and surrounds, 30º17’33.1”S 69º46’45.6”W, 4005 m a.s.l., C. Mattoni & A. Ojanguren coll., 27/I/2005, UV sampling, 2 males and 2 females ( AMNH); (same data) 2 males and 2 females ( CDA); (same data) 4 males, 4 females, 2 juveniles (MACN-Ar). Mendoza Province, Laguna Diamante , 34º11´47,22", 69º22´29,4", 3344 m a.s.l., F. Fernández Campón & S. Lagos Silnik coll., 17/II/2005, 11 males (MACN-Ar); 34º14' 24,48", 69º30' 22,08", 3573 m a.s.l., 17/II/05, 5 males, 1 female, 5 juveniles, (IADIZA); 34º11´50,16"S; 69º32´10,32"W, 3398 m a.s.l., 24/II/06, 26 males, 1 female, 1 juvenile, (IADIZA); 34º 14´22,86", 69 30´27,96", 3574 m a.s.l., 24/II/06, 1 male, 1 female, 1 juvenile, (IADIZA). Las Cuevas, 32º 48´34,98", 70 04´16,44", 3329 m a.s.l., F. Fernández Campón & S. Lagos Silnik coll., 26/II/06, 1 male, 1 female, 1 juvenile, (IADIZA). Puente del Inca, Mendoza, (2700 m a.s.l., G. Flores & J.A. Ochoa coll., 15/XII/2001, 1 juvenile (IADIZA).

Remarks. Acosta (2005) made an excellent taxonomic and historic revision of Orobothrius bivittatus . He deduced the actual type locality of O. bivittatus , somewhere in the Tontal mountain chain. He studied the species holotype, a poorly preserved juvenile, as well as a single adult male specimen collected by him in this area. Based on this material he considered O. bivittatus as a valid species closely related to O. alticola . Later, Acosta (2006) applied to the International Commission of Zoological Nomenclature (ICZN) to designate as a neotype the recently collected adult male, to replace the juvenile holotype, which does not show many diagnostic features (including the hemispermatophore). The proposed replacement of the holotype was not accepted by the ICZN, because the original material still exists and, according to them, there is no exceptional need to designate a neotype (ICZN, 2008).

However, when trying to support the recognition of O. bivittatus as a different species (separated from O. alticola ), Acosta (2005: p. 8) stated:

“Similarities concern both the pigment pattern and the external morphology, being difficult indeed to find a sharp morphological discrimination. Only the hemispermatophore provides reliable differences. The fact that just one male of O. bivittatus is hitherto available – i.e. variability remains unknown – lessens to some extent the strength of these conclusions, but the differences encountered, together with the apparent geographical isolation, support the latter being regarded as an independent entity.”

Acosta (2005) mentioned several differences between O. alticola and O. bivittatus : (1) the apex of the hemispermatophore is proportionally shorter in O. alticola than in O. bivittatus , representing a 38% of the total length of the distal lamina in the first species and a 47% in O. bivittatus , this being the most remarkable difference between species. He also mentioned that in O. bivittatus the upper margin of the frontal crest forms a spur like projection that is not present in O. alticola . (2) Orobothriurus alticola males bear VSM carinae on metasomal segment II that are absent in O. bivittatus . (3) Orobothriurs alticola has metasomal segment IV with 6 VSM macrosetae whereas O. bivittatus bears 8. (4) Orobothriurus alticola males measures 27 to 31.5 mm, whereas the single specimen of O. bivittatus was only 24.4 mm.

In a recent trip to the Tontal mountain chain we have collected several specimens of Orobothriurus in the same area where Acosta collected the single adult specimen mentioned in his publication. This new material allowed us to assess the morphological variability of the population. Acosta (2005) did not gave details about the protocol used to measure the distal lamina of the hemispermatophore and its apex, neither did he give a range of variability of hemispermatophore relative length in O. alticola although he had access to several specimens of this species. Since there is some degree of variability in the shape and size of the hemispermatophore apex in Orobothriurus species, a figure showing the way we measured this structure ( Fig. 18 ) is presented, as well as photos of hemispermatophores of several O. alticola specimens from different Andean populations, and from the Orobothriurus population of El Tontal ( Figs. 25 ─34). We measured the total length of the distal lamina and the apex of the distal lamina. We found that in Andean O. alticola specimens the apex represents a 40.87 to 45.33% of the total length of the distal lamina (N=11, media=43.16), whereas in the specimens from the Tontal it represents a 43.58 to 46.08 % (N=8, media=44.46). The ANOVA statistical analyses of the relation length of the apex / length of distal lamina, including measures from O. grismadoi as well, cannot distinguish any differences between the populations ( Table 2 ). There are not significant differences also between O. alticola specimens from El Tontal and from the Andes regarding the angle between the apex and the distal lamina ( Fig. 19 ), ( Table 2 ). The spur like projection of the frontal crest is present in some specimens from El Tontal as well as in some specimens of Andean populations of O. alticola ( Figs. 25 ─34).

Males of O. alticola of Andean localities, as well as specimens from El Tontal usually do not bear VSM carinae in metasomal segment II, however some specimens in both populations have vestigial VSM carinae. The VSM setae of metasomal segment IV vary from 6 to 8 in specimens from El Tontal (N=21; median=7), and in Andean specimens of O. alticola they vary from 6 to 9 (N=12; median=7).

Total length of males specimens from El Tontal studied by us ranges from 25 to 31 mm (N=8; media=27.80 mm), whereas the total length of O. alticola males ranges from 26.9 to 31.5 mm (mean=28.7 mm) in specimens from Puente del Inca, from 27.1 to 31.5 mm (mean 28.9 mm) in specimens from Paso del Agua Negra (Acosta 2005); and from 32 to 36.5 mm in specimens from Laguna Diamante (N=11; mean 34.1 mm).

Acosta (2005) mentioned that the tergite VII of the adult male specimen from El Tontal he studied was almost completely covered by pigment, without a median unpigmented stripe. This is an unusual characteristic in this genus that could be a strong diagnostic character ( Ochoa 2004). However, only 3 of the 21 specimens from El Tontal revised by us share this character, being the rest of the specimens similar to the Andean specimens of O. alticola .

The specimens of Orobothriurus from El Tontal we studied were collected in the same area, altitude, and environment as the Acosta’s adult male specimen. The morphological characteristics of El Tontal specimens are similar to those of the specimens studied by Acosta, and no sympatric species are known to occur in this genus. Therefore we consider El Tontal and Acosta’s specimens to the be the same species. According to our results Orobothriurus specimens from El Tontal cannot be distinguished from the Andean specimens of O. alticola , so we decided to consider them as belonging to the same species, therefore synonymising O. bivittatus with O. alticola . The name Orobothriurus bivittatus ( Thorell 1877) should have priority over Orobothriurus alticola ( Pocock 1899) . However this change would threaten nomenclatural stability (Acosta 2002; ICZN 2004) so the name O. alticola should be preserved over O. bivittatus .

In upper level of El Tontal mountain chain O. alticola is sympatric with Brachistosternus montanus Roig Alsina 1977 , this being the first record of this species in the Precordillera. This Andean species of scorpion occurs in the same altitudes and environments as O. alticola , and has a similar distribution in the Andean sector of central western Argentina (Ojanguren Affilastro 2003b, 2005).

Comments: Because of the high distance that separates it from the Andes mountain chain (200 km), the upper level of the Nevado orographic system is an area of endemism for high altitude arthropod fauna, with closely related species found at high altitude locations in the Andean range. Roig-Juñent et al. (2007) have described a species of carabid beetle, Cnemalobus nevado Roig-Juñent et al. 2007 , from the same sites where O. grismadoi was collected. Its sister species, Cnemalobus diamante Roig-Juñent et al. 2007 , occurs in high altitude locations in the Andean range (Laguna Diamante , Mendoza) ( Roig-Juñent et al. 2007). Another closely related species, Cnemalobus mendozensis Roig-Juñent 1993 , inhabits the plateau connecting both high altitude sites ( Roig-Juñent 1993). Other endemics to the Nevado are carabid beetles such as Baripus nevado Roig-Juñent et al. 2008 , Trechisibus nevadoi Roig-Juñent & Sallenave 2005 ( Roig-Juñent et al. 2008) , and tenebrionid beetles of the genus Nyctelia Latreille, 1925 ( Flores & Carrara 2006) and Falsopraocis Kulzer, 1958 ( Flores, 2000) .

The upper level of the Tontal orographic system could also be considered as another area of endemism for high altitude arthropod fauna, with one species of tenebrionid beetle recently described for that area, Psectracselis argentina Flores 2007 ( Flores 2007). However, our results show that this is not the case for scorpions, with both east Andean scorpion species known from this latitude present in the Tontal ( O. alticola and B. montanus ). Even if nowadays the Puna and high Andean vegetation of the upper level of the Tontal (where both species are restricted) are isolated from that of the Andes, the distance that separates both is only about 50 km ( Fig. 35 ), (compared to the 200 km that separate the Nevado from the Andes), with an area of intermediate altitude between them. This could have favoured the flow of the scorpion fauna between both areas up to a recent past.

Figures

FIGURE 35. Map of central Argentina showing the known distribution of the Orobothriurus species of the area.

FIGURES 1 – 5. 1, 3 – 5. Orobothriurus grismadoi n. sp.. 1. Telson, male, lateral aspect; 3. Telson, female, lateral aspect; 4. Sternite VII and metasomal segment I, female, ventral aspect; 5. Metasomal segment V, male, ventral aspect. 2. Orobothriurus alticola. Telson, male, lateral aspect. Scale bars: 1 mm.

FIGURES 16 – 19. Left hemispermatophore. 16, 17. Orobothriurus grismadoi n. sp. 16. Internal aspect; 17. External aspect. 18. Orobothriurus alticola, (El Tontal, San Juan province, Argentina), external aspect, showing the distal lamina measures analyzed: A = apex length, B = distal lamina length. 19. Orobothriurus alticola, (Puente Del Inca, Mendoza province, Argentina), external aspect, showing the angle (C) between apex and distal lamina base. Scale bars: 1 mm.

FIGURES 20 – 34. Left hemispermatophores, distal lamina, external aspect. 20 – 24. Orobothriurus grismadoi n. sp.. 25 – 34. Orobothriurus alticola. 25. Puente del Inca, Mendoza province, Argentina; 26 – 28. Paso del Agua Negra, San Juan province, Argentina; 29. Laguna Diamante, Mendoza province, Argentina; 30 – 34. El Tontal, San Juan province, Argentina. Scale bars: 1 mm.

Tables

TABLE 2. Results of ANOVA one-way analyses assessing variability between hemispermatophore of different Orobothriurus populations. Values are expressed as the mean ± standard deviation. Letters in bold indicate results from Tukey-Kramer Multiple-Comparison Test: equal letters mean homogeneous groups. Abbreviations: F = F-ratio ANOVA statistic; P = probability of equal medians (* indicates significant differences); N = sample size.

	Orobothriurus grismadoi Orobothriurus alticola (Andean specimens)	Orobothriurus alticola (El Tontal specimens)
Relation apex/lamina	0.442±0.009 0.432±0.014	0.445±0.010
N	7 11	8
F= 3.19, P= 0.06	A A	A
Angle apex-lamina base (on degrees)	137.14±1.96 141.21±2.22	142.20±2.79
N	5 5	5
F= 6.50, P= 0.012*	A B	B