Brachistosternus philippii, Ojanguren-Affilastro & Pizarro-Araya & Ochoa, 2018

Ojanguren-Affilastro, Andrés A., Pizarro-Araya, Jaime & Ochoa, José A., 2018, Five new scorpion species of genus Brachistosternus (Scorpiones: Bothriuridae) from the deserts of Chile and Peru, with comments about some poorly studied diagnostic characters of the genus, Zootaxa 4531 (2), pp. 151-194 : 162-169

Brachistosternus philippii n. sp.

( Figs. 1 , 2B , 7 , 8 , 9 A–C, 10, 11, 26A, B; Table 1 )

Type material. Holotype male: Chile, Antofagasta Region, Paposo Norte Natural Monument, about 60 km N. from the Village of Paposo (24°32'30.23''S, 70°34'19.40'' W), 1 m asl, (dunes close to the beach), 19/XI/2014. A. A. Ojanguren-Affilastro, J. Pizarro-Araya, F. M. Alfaro, P. Agusto, J. E. Barriga ( MNHN) ; Paratypes (same data as holotype): 1 female ( MNHN) ; 5 males, 5 females, ( MACN) ; 1 male, 1 female ( MZUC) ; 1 male, 6 females ( LEULS) .

Etymology. This species is named after the German naturalist Rodulfo Amando Philippi Krumwiede, who surveyed most of Chile, including its northern deserts, and who directed the Museo Nacional de Historia Natural in Santiago ( Chile), between 1853 and 1897.

Diagnosis. Brachistosternus philippii n. sp. is a member of the subgenus Brachistosternus because of the trichobothrial pattern and the shape of the hemispermatophore. It is a typical species of lowland deserts of Northern Chile and Southern Peru. Brachistosternus philippii n. sp. is the only known species from the western slopes of the Andes which presents, in most of its specimens, the orthobothriotaxic type C trichobothrial pattern in its pedipalp chela. About 50 % of the specimens bear four ventral trichobothria in their pedipalp chela, the remaining 50 % only three ( Figs. 8 B, F ), whereas rest of the species of the area always bear five ventral trichobothria; 70 % of the specimens of B. philippii n. sp. missing eb5 trichobothrium of patella and 30 % missing em1, whereas in remaining species of the area these trichobothria are always present. Brachistosternus philippii n. sp. is most closely related to Brachistosternus mattonii Ojanguren-Affilastro (2005) , with which it shares a very similar external morphology and a very similar hemispermatophore. Both species can be easily separated (besides the trichobothrial pattern), because metasomal segments IV and V of B. philippii n. sp. ( Figs. 9 A–C) are more slender and less granular than in B. mattonii ( Figs. 9 D–F). Length/width ratio of metasomal segment IV: B. philippii n. sp. males: 1.91–2.09 (N=5; mean=1.98), B. mattonii males: 1.55–1.72 (N=5; mean=1.66); B. philippii n. sp. females: 1.77–1.94 (N= 5; mean=1.86); B. mattonii females: 1.67–1.76 (N=5; mean=1.73). Length/width ratio of metasomal segment V: B. philippii n. sp. males: 2.02–2.24 (N=5; mean=2.13), B. mattonii males: 1.78–1.95 (N=5; mean=1.86); B. philippii n. sp. females: 1.94–2.06 (N=5; mean=1.99); B. mattonii females: 1.85–1.95 (N=5; mean= 1.89).

Description. Based on the holotype male (MNHN) and paratypes (MACN, LEULS, MZUC). Total length: 52– 58 mm in males (N=8; mean= 55.63mm); 53–63 mm in females (N=7; mean= 57mm). Colour: Base colour light yellowish, with brown pigmentation pattern in carapace and tergites ( Figs. 7 A–D). Chelicerae unpigmented. Carapace, anterior margin and area anterior to the ocular tubercle with faint reticular pigment pattern; ocular tubercle black; with two broad brown stripes from the postocular furrow to the lateral ocelli; with two small posterolateral dark spots. Tergites I–VI each with two well developed lateral dark spots connected by faint reticulate pigment. Tergite VII with two faint posterolateral lateral dark spots. Sternites, sternum, genital opercula, pectines and metasomal segments unpigmented. Telson , vesicle unpigmented; aculeus dark brown. Pedipalps: trochanter unpigmented; femur with stripes along DE and VE margins, joining in a dark dorsal spot near the articulation with patella. Patella with dorsointernal, external and ventroexternal stripes. Chela unpigmented. Legs: coxae and trochanters unpigmented; femora with faint pigment pattern in posterior margin; patellae with faint pigment pattern along anterior margin; tibiae, basitarsi, and telotarsi unpigmented.

Chelicerae: anterior margin of movable fingers strongly curved in males, less curved in females; movable fingers with two very small subdistal teeth, the basal twice bigger than the distal.

Pedipalps: Femur with DI, DE and VI carinae well developed, extending the entire length of segment, VE carinae represented by scattered granules in basal third of the segment ( Fig. 8H ); with two DE macrosetae; anterior margin with scattered medium sized granules and one macroseta; posterior margin with four to six macrosetae, rest of the intercarinal surfaces smooth. Patella, DI and VI carinae well developed and extending entire length of segment, external surface granular ( Fig. 8G ); with one DI macroseta and two VI macrosetae. Chela manus slender, slightly more robust in males, length/width ratio males: 4.25–4.56 (N=6; mean=4.46), females: 4.45–4.66 (N=6; mean=4.56); the length/height ratio males: 3.32–3.42 (N=6; mean=3.48), females: 3.26–3.75 (N=6; mean=3.50); with a VM accessory carina, blunt in females, slightly granular in males; internal surface with slight bulge near articulation of movable finger (females) ( Fig. 8E ), or with a pronounced, subtriangular projection (males) ( Fig. 8A ), with a conspicuous constriction near the apex, and in some specimens with a bifurcate apex; fingers elongated, with a median row of denticles, and seven or eight pairs of accessory denticles in fixed and movable fingers ( Fig. 8D ), the basal external denticle is usually part of the median row. Trichobothrial pattern orthobothriotaxic Type C, femur with 3 trichobothria (d, i, e), one macroseta (M1) between with d and i; patella with 19 trichobothria (2 d, i, 3 et, est, 2 em, 2 esb, 5 eb, 3 V), with esb 2 petite; chela with 26 trichobothria (Dt, Db, 5 Et, Est, Esb, 3 Eb, dt, dst, dsb, db, et, est, esb, eb, ib, it, 4 V), with Et 4 petite, Esb forming triangle with Eb 2 and Eb 3 ( Fig. 8C ). About 50 % of the specimens neobothriotaxic minor type C, with V4 trichobothrium missing in V series of chela ( Figs. 8B, F ); 70 % of the specimens missing eb5 trichobothriium of patella, and 30 % missing em1 ( Fig. 8G ).

Carapace: anterior margin slightly convex, with four or six short macrosetae, and a well developed median projection. Surface: finely granular, except the median dorsal area that is smooth. Anterior longitudinal sulcus, posterior longitudinal sulcus, and lateral sulci present and well developed in males, less developed in females. Median ocular tubercle well developed, in the middle of the carapace, with a shallow interocular sulcus and some anterior granules, median ocelli medium sized, facing towards the lateral margins, ca three diameters apart; with one seta behind each eye. Lateral ocelli pattern type 3A; with three small lateral ocelli on a prominence on each side of carapace, two of them anteriorly, the anterior one slightly above the posterior one, third ocellus half of the size to the other two, slightly above the others.

Legs: Surfaces smooth, except for the external surface of femora of legs III and IV which are slightly granular, more so in males. Basitarsi each with two well developed pedal spurs, internal one 30% smaller than the external one in legs I and II, symmetrical in legs III and IV. Telotarsi elongated, ventrolaterally compressed, dorsally with a row of setae, ventrally each with a ventromedian row of medium sized hyaline setae, and paired rows of ventrosubmedian setae. Telotarsus of leg III: Dorsal setae: 11–13 (N=11; median=13); ventrosubmedian prolateral setae: 7–9 (N=11; median=8); ventrosubmedian retrolateral setae: 4–6 (N=11; median=6). Ungues shallowly curved, asymmetrical in legs I and II, retrolateral one about 30 % smaller; equal in length in legs III and IV; telotarsus IV more elongated than the rest, with slightly longer and less curved ungues than the rest of the tarsi.

Pectines: elongated, with small teeth. Tooth count males: 31–34 (N=6; median=32); females: 25–30 (N=4; median=29); internal basal lamella of females more elongated than in males.

Sternum: With two subtriangular lateral lobes, each with a stout, club shaped macroseta, ( Fig. 26A, B ).

Genital opercula: Sclerites subtriangular, similar in males and females.

Tergites: I–VI with two dorsosubmedian setae, surface smooth in the median area, slightly granular in lateral and posterior margins, more so in males, with the granules occupying the posterior third of the segment; tergite VII with two dorsosubmedian setae; slightly granular in the median part of the anterior margin, densely granular in the lateral margins; with two dorsosubmedian carinae in the posterior third, and two lateral carinae in posterior two thirds of the segment.

Sternites: Sternites III-VI surface smooth in females, covered by medium sized granules in males; with large and elongated spiracles, and paired submedian furrows, shallow and subcircular in females, deeper and elongated in males; sternite VII slightly granular in females, densely granular in males.

Metasoma: Metasomal segment I, dorsal surface densely granular, except for a smooth area around the median sulcus; DL carinae extending the entire length of the segment; lateral surfaces granular; LM carinae present in the posterior two thirds of the segment, LIM carinae only present in the posterior half of the segment; with one LIM macroseta in the posterior third of the segment; ventrally without carinae, finely granular in males, smooth in females, with two pairs of VL setae in the posterior half of the segment (2-2), and two posterior VSM setae. Metasomal segments II and III similar to segment I but less granular; with a DL and a LM setae; the LIM carinae is restricted to the posterior third in segment II, and absent in segment III. Metasomal segment IV, dorsal surface with scarce granulation; DL carinae extending the entire length of the segment, connected with the lateral accessory carinae which is present in the posterior third of the segment; lateral surfaces densely granular ( Fig. 9C ); LM carinae represented by two setae; LIM carinae represented by two posterior setae; ventrally finely granular in males ( Fig. 9B ), almost smooth in females; with scattered setae ranging from 30 to 34. Metasomal segment V elongated, length/width ratio, males: 1.81–2.01 (N=6; mean=1.93); females: 1.85–1.97 (N=5; mean=1.91); dorsal surface smooth medially, with two elongated and narrow glands or androvestigia in anterior two thirds of the segment ( Fig. 10 C ), densely granular in the DL margins, but not forming a carina; lateral margins granular, more so in males ( Figs. 10A,B ); LM carinae represented by some scattered granules and a row of six to eight setae; ventral surface with abundant medium sized granules, VM carina granular ( Fig. 9A ), straight, extending the entire length of the segment, with its posterior third becoming wider posteriorly; usually with three transverse rows of macrosetae, one near the anterior margin of four macrosetae, and two of two macrosetae each, in the median part of the segment (distribution 4-2-2), in some specimens there is an additional row of two setae near the posterior margin; VL carinae granular, straight, and extending the entire length of the segment, with 9 to 13 VL macrosetae (N=24; median=11).

Telson: Vesicle relatively globose, slightly lower in some males ( Figs. 10 A, B ); length/height ratio, males: 3.32–3.69 (N=6; mean=3.42), females: 3.16–3.65 (N=5; mean=3.35); ventral and lateral margins with scattered blunt granules in females, densely granular in males; ventrally with two shallow VSM furrows surrounding a VM granular area, with three or four pairs of VSM and two or three pairs of VL macrosetae; laterally with a conspicuous furrow on each side; dorsal surface smooth and shallow, males with a barely visible glandular surface, only marked by a shallow pit. Aculeus longer than the vesicle, shallowly curved; more so in males.

Hemispermatophore: Basal portion well developed. Distal lamina well developed, similar in length to the basal portion ( Fig. 11A ); apex gently inclined towards the internal margin, distal crest medium sized, occupying the apical third of the distal lamina, and with some small transverse keels in its basal half; distal lobe (distal posterior flexure) elongated, occupying about the basal third of the distal lamina. Left hemispermatophore: cylindrical apophysis of the basal lobe well developed ( Fig. 11B ), slightly wider in its median part, and with an acute and curved tip, barely reaching the base of the distal lobe, and slightly longer than the laminar apophysis; laminar apophysis clearly bilobed, with a well developed median longitudinal flexure that divides it into two conspicuous lobes; row of spines and basal spines well developed and in the same line, internal spines present and well developed; basal triangle well developed, formed by three or four chitinous crests and some scattered granules. Right hemispermatophore without a cylindrical apophysis ( Fig. 11C ), with a medium sized ILA chitinized, and with small to medium sized spines in its anterior and dorsal margins; the rest as left hemispermatophore.

Distribution. Brachistosternus philippii n. sp. has only been collected in a single spot of the coast of Antofagasta region in Chile ( Fig. 1 ). This area corresponds to the Paposo Norte Natural Monument (Antofagasta Region).

Ecology. Brachistosternus philippii n. sp. has been collected in the coastal dunes in northern Chile, in the few places of the area that harbor some vegetation, which is reduced to some scattered plants adapted to psammophilous environments as Nolana sedifolia Poepp. , Atriplex taltalensis I. M. Johnston and Frankenia chilensis C. Plesl. ( Fig. 2B ). No specimens of B. philippii n. sp. have been collected by the tide line, an environment occupied slightly northerly by its sister species B. mattonii ( Ojanguren-Affilastro et al. 2016b). No other scorpion species has been collected in sympatry with B. philippii n. sp.

All known specimens of B. philippii n. sp. have been collected in summer, which suggests that this species has a spring-summer activity period, as all known Brachistosternus species from the area.

Figures

FIGURE 1. Distribution map of Brachistosternus gayi n. sp., Brachistosternus philippii n. sp., Brachistosternus contisuyu n. sp., Brachistosternus misti n. sp. and Brachistosternus anandrovestigia n. sp.

FIGURES 2A–F. Type locality of Brachistosternus species herein described. A. Brachistosternus gayi n. sp.; B. Brachistosternus philippii n. sp.; C. Brachistosternus contisuyu n. sp.; D, E. Brachistosternus misti n. sp.; F. Brachistosternus anandrovestigia n. sp.

FIGURES 7A–D. Brachistosternus philippii n. sp., habitus. A. Male, dorsal aspect; B. Male, ventral aspect; C. Female, dorsal aspect; D. Female, ventral aspect. Scale bars: 1 cm.

FIGURES 8A–H. Brachistosternus philippii n. sp. A. Right pedipalp chela, male, internal aspect; B. Right pedipalp chela, male, ventral aspect; C. Right pedipalp chela, male, external aspect; D. Right pedipalp chela, male, dorsal aspect; E. Right pedipalp chela, female, internal aspect; F. Right pedipalp chela, female, ventral aspect; G. Right pedipalp patella, male, external aspect; H. Right pedipalp femur, male, dorsal aspect. Scale bars: 1mm.

FIGURES 9A–F. A–C. Brachistosternus philippii n. sp. A. Metasomal segment V, male, ventral aspect; B. Metasomal segment IV, male, ventral aspect; C. Metasomal segment IV, male, lateral aspect. D–F. Brachistosternus mattonii. D. Metasomal segment V, male, ventral aspect; E. Metasomal segment IV, male, ventral aspect; F. Metasomal segment IV, male, lateral aspect. Scale bars: 1mm.

FIGURES 10A–C. Brachistosternus philippii n. sp. A. Metasomal segments IV, V and telson, male, lateral aspect; B. Metasomal segment V and telson, female, lateral aspect; C. Metasomal segment V, male, dorsal aspect. Scale bars: 1mm.

FIGURES 11A–C. Brachistosternus philippii n. sp. A. Left hemispermatophore, external aspect. B. Left hemispermatophore, detail of the lobe region; C. Right hemispermatophore, detail of the lobe region (ILA = Internal Lateral Apophysis). Scale bars: 1mm.

FIGURES 26A–D. A, B. Brachistosternus philippii n. sp. A. Sternum macroseta; B. sternum macroseta, detail of the apex. C, D. Brachistosternus multidentatus. C. sternum macroseta; D. sternum macroseta, detail of the apex. Scale bars: A. 200 µm; B. 50 µm; C. 500 µm; D. 10 µm.