Pseudouroctonus sprousei, Francke, Oscar F. & Savary, Warren E., 2006

Francke, Oscar F. & Savary, Warren E., 2006, A new troglobitic Pseudouroctonus Stahnke (Scorpiones: Vaejovidae) from northern México, Zootaxa 1302, pp. 21-30 : 23-29

Pseudouroctonus sprousei , new species

( Figs. 1–14 )

Type data. Holotype male from MEXICO: Coahuila; El Abra (cave), El Remolino (UTM NAD27: 14R: 267620, 3180825, elev. S 530 m.) [N 28o 44´0.5´´ W–101o 22´45´´] 29 April 2001, 17 Feb. 2002 (the specimen label bears two dates, on both of which the cave was explored; the collector indicated the second date is probably when the specimen was actually collected). Peter Sprouse. Deposited in the Colección Nacional de Arácnidos ( CNAN T­0202), Departamento de Zoología, Instituto de Biología, Univ. Nacional Autónoma de México.

Distribution. Known only from the holotype.

Diagnosis. Differs from all other Pseudouroctonus species by having a distinct patellar internomedian carina and by its large size, with the only adult specimen known measuring 74 mm in length. Differs from P. l i n d s a y i and the species in the former minimus group in having a distinct white patch on the pedipalp chela finger tips, in having prominent teeth ventrally on the fixed and movable fingers of the chelicera, and in having 17 pectinal teeth in males. Further differs from the members of the former minimus group in lacking a distinctive tooth on the lateral lobe of the lamellar hook of the hemispermatophore, and differs from P. lindsayi in having the lamellar hook elevated from the lamella base. It is most closely related to P. re d d e l l i, the type species of the genus, based on hemispermatophore morphology, cheliceral dentition, pedipalps finger terminating in a white patch, and elevated pectinal tooth count. Differs from P. reddelli in size, being almost 50% larger; in color, being medium brown without fuscosity ( P. reddelli is dark reddish brown and heavily infuscate); in having metasomal segment I clearly longer than wide (subequal in P. re d d e l l i); in having the pedipalp femur and patella longer than the carapace (shorter or subequal in P. reddelli ); and in bearing seven rows of denticles clearly defined by six enlarged primary denticles on the movable finger of the pedipalp chela ( P. reddelli has six rows defined by five primary denticles.

Description. Based on the adult holotype male and only known specimen ( Fig. 1 ).

Color: Medium brown; venter and legs ochre/yellow, without fuscosity.

Carapace: Longer than wide. Median eyes on anterior 35%. Ocular tubercle low, without superciliary crests. Median eyes reduced in size, 0.2 mm in diameter. Three pairs of lateral eyes, somewhat reduced in size; posterior­most eye is about ½ diameter of anterior two. Anterior median furrow shallow and broad. Posterior median furrow deep and narrow, the median lobes meeting medially over the furrow. Posterolateral furrows deep and broad. Anterior margin broadly bilobed, with 3 pairs of setae. Entire surface with moderately dense, fine granulation.

Tergites: With moderately dense, fine granulation. Tergite VII with four denticulate, longitudinal carinae.

Sternum: Subpentagonal, slightly longer than broad; median longitudinal furrow deep and narrow; with seven setae (asymmetrical).

Genital operculi: With five setae each; genital papillae well developed, protruding beyond the genital operculi.

Pectines: With 10–11 middle lamellae; 17 teeth on each side.

Sternites: Glabrous. Stigmata slit­like, about 3.5 times longer than wide. Sternite VII with one pair of moderately strong, denticulate lateral carinae. Metasoma: Dorsolateral carinae on I–V strong, denticulate/serrate. Lateral supramedian carinae on I–IV strong, denticulate/serrate. Lateral inframedian carinae on I strong, denticulate, complete; on II represented by 3–4 granules distally; on III by one single granule distally; on IV absent. Lateral median carina on V granular on basal one­third. Ventrolateral carinae on I–V, ventral submedian carinae on I–IV and ventral median carina on V strong, denticulate/ serrate. Setation on I–IV: dorsolaterals 0,1,1,2; lateral supramedian 0,1,1,1; lateral inframedian 1,0,0,0; ventrolateral 2,2,2,3; ventral submedian 3,3,3,4. Setation on V: dorsolateral 3, lateromedian 2, ventrolateral 3 and ventromedian 4. Intercarinal spaces densely, minutely granulose (matte).

Telson: Vesicle large and globose ( Fig. 2 ), more swollen than that of P. reddelli ( Fig. 3 ); weakly to faintly granulose, sparsely setose. Aculeus lacking basal microdenticles.

Chelicera: Fixed finger shorter than chela width, movable finger shorter than chela length. Chela with 2 setae dorsally. Fixed finger with basal bicusp symmetrical; ventral margin with 3 prominent accessory denticles ( Fig. 4 ). Movable finger with two dorsal subdistal teeth; with a distinct serrula ventrally, and with ventral carina strongly delineated, bearing three large and several small denticles ( Fig. 4 ).

Pedipalp femur: Dorsointernal, dorsoexternal and ventrointernal carinae strong, coarsely granulose; ventroexternal carina obsolete; internomedial carina represented by 4–5 isolated granules which decrease in size distally. Orthobothriotaxia “C” ( Fig. 5 ). Dorsal face with dense, small granulation; internal face with three submedian setae; external face with four median setae; ventral face with moderately dense granulation, decreasing in size distally.

Pedipalp patella: Internomedian carina represented by a row of 7–8 prominent granules spread on basal two­thirds, decreasing in size distally and angling slightly dorsally; dorsointernal carina strong, coarsely granulose; dorsoexternal carina strong, scabrose; ventrointernal carina strong, coarsely granulose; ventroexternal carina strong, scabrose. Orthobothriotaxia “C” ( Figs. 6–8 ). Intercarinal spaces dorsally matte, matte to glabrous on others.

Pedipalp chela: Carinae scabrous to granulose; intercarinal spaces lustrous. Finger tips with distinctive white patches distally. Fixed finger with 6 rows of granules and 6 inner accessory denticles; movable finger with 7 rows of granules and 7 inner accessory denticles. Orthobothriotaxia “C” ( Figs. 9–11 ).

Leg III telotarsal armature ( Figs. 12–14 ): two prolateral inframedian setae; two retrolateral inframedian setae; two prolateral infraterminal setae; two retrolateral infraterminal setae. Ventral median spinules: basal cluster, distally with 4–5 spinules.

Hemispermatophore: with dorsal hook on basal 28% of lamina ( Fig. 15 ). Bears a thickened, acuminate lateral hook connected to the lamella by an elevated lateral flange ( Figs. 16–17 ); mating plug with distal barb margin smooth ( Fig. 18 ). Resembles that of P. reddelli ( Figs. 19–21 ).

Measurements (in mm). Total L 74.1; carapace L/ W 8.6 /7.0; distance from anterior margin to median eyes 3.2; mesosoma L 18.4; metasoma total L 47.1; segment I L/ W 5.0 / 3.6; II L/ W 6.0 /3.4, III L/ W 6.3 /3.2; IV L/ W 7.8 /3.0; V L/W/D 11.8/2.8/2.5; telson L/W/D 10.2/3.2/3.3; chelicera L/ W 3.4 /1.8, fixed finger L 1.0, movable finger L 2.0; pedipalp femur L/ W 9.2 /2.4; pedipalp patella L/ W 9.2 /2.6; pedipalp chela L/W/D 15.6/3.5/4.3, fixed finger L 6.2, movable finger L 7.6. Hemispermatophore L 8.0, lamina L 5.0.

Etymology. This species is dedicated to Mr. Peter Sprouse, a tireless explorer of Mexican caves and collector of numerous troglobites, including the holotype of this new taxon.

Comments. Pseudouroctonus sprousei has median and lateral eyes (these somewhat reduced in size), so it has not reached the extreme condition of eyelessness observed in other Mexican cave scorpions (e. g., some Typhlochactas Mitchell , Sotanochactas Francke , Troglocormus Francke , and Alacran Francke ). Although P. reddelli has been collected in numerous caves (as well as many surface locations) in Texas and Coahuila, it has no apparent morphological modifications for life in caves. It is hypothesized that P. sprousei is troglobitic when compared to P. re d d e l l i, its putative closest relative: it is considerably paler in color; the metasoma is elongated [apparent when the length/width ratio of segment I (close to 1.5 in P. sprousei ) is compared to that of P. reddelli (approximately equal to 1)]; and the pedipalps are attenuated [apparent when the relative lengths of the femur and patella are compared with the carapace length in the two sister species—subequal in P. reddelli and longer in P. sprousei ]. This hypothesis awaits further testing by the collection of additional specimens and data on their habitat and biology. Among the Vaejovidae , three troglophiles (without obvious cave adaptations or troglomorphies) are known: P. reddelli , Vaejovis norteno Sissom and Gonzalez­Santillán from Coahuila and Nuevo León, México, and Vaejovis davidi Soleglad and Fet from Puebla, México. An additional troglophile, Uroctonites sequoia (Gertsch and Soleglad) from California, has the number of lateral eyes reduced in most specimens, but is known from at least one epigean locality. Two other vaejovids, Uroctonus grahami (Gertsch and Soleglad) from California, and Vaejovis gracilis Gertsch and Soleglad from Veracruz, appear to be true troglobites (they are known only from inside of caves) and exhibit distinct cave adaptations (e. g., reduced eye size and reduced pigmentation compared to their closest relatives).

Figures

FIGURE 1. Dorsal view of holotype male of Pseudouroctonus sprousei, sp. nov.

FIGURES 2 – 8. Morphology of Pseudouroctonus sprousei, sp. nov. and P. reddelli: 2. Metasomal segment V and telson of P. sprousei, lateral view; 3. Metasomal segment V and telson of P. reddelli, lateral view; 4. Chelicera of P. s p ro u s ei, ventral view showing diagnostic dentition on both fingers; 5. Pedipalp femur of P. s p ro u s e i, dorsal view showing trichobothrial pattern; 6. Pedipalp patella of P. s p ro u s e i, dorsal aspect; 7. pedipalp patella of P. s p ro u s e i, external aspect showing trichobothrial pattern; 8. Pedipalp patella, ventral aspect (Scale figs. 2, 3 = 5 mm, figs. 4 – 8 = 1 mm).

FIGURES 9 – 14. Morphology of Pseudouroctonus sprousei, sp. nov.: 9. Pedipalp chela, dorsal aspect; 10. Pedipalp chela, external aspect; 11. Pedipalp chela, ventrointernal aspect; 12. Telotarsus III, prolateral aspect showing setation pattern; 13. Telotarsus III, ventral aspect, schematic showing ventromedian spinules and setae; 14. Telotarsus III, retrolateral aspect (scale figs. 9 – 11 = 1 mm, figs. 12 – 14 = 0.5 mm).

FIGURES 15 – 21. Hemispermatophores of Pseudouroctonus sprousei, sp. nov. and P. reddelli: 15. Hemispermatophore of P. s p ro u s e i, dorsal aspect; 16, 17. Details of lamellar hook and capsular region of P. sprousei, mating plug removed; 18. Mating plug from the hemispermatophore of P. sprousei; 19. Hemispermatophore of P. reddelli, dorsal aspect; 20, 21. Details of lamellar hook and capsular region of P. reddelli, mating plug in place (scale figs. 15, 19 = 0.67 mm, 16, 17, 20, 21 = 1 mm, 18 = 0, 5 mm).