Typhlochactas sissomi, Francke & Vignoli & Prendini, 2009

Francke, Oscar F., Vignoli, Valerio & Prendini, Lorenzo, 2009, A New Species of Typhlochactas (Scorpiones, Typhlochactinae) from Eastern Mexico, American Museum Novitates 3647, pp. 1-12 : 5-10

Typhlochactas sissomi , n. sp.

Figures 1 –7, table 2

TYPE MATERIAL: Holotype: 1 subadult $ ( CNAN T-0308 ), leg ( AMCC), Mexico: Queretaro: Municipio de Jalpan : Cañada de La Joya, 21 ° 27 9 23 0 N 99 ° 08 9 26 0 W, 1944 m, H. Montaño and A. Valdez, 12.vi.2004, rock-rolling.

ETYMOLOGY: The new species is named in honor of Dr. W. David Sissom, West Texas A&M University, Canyon, Texas, U.S.A., for his numerous contributions to scorpion taxonomy .

DIAGNOSIS: Typhlochactas sissomi differs from all other species in the genus on the basis of the following combination of characters: cheliceral fixed finger with four teeth, median and basal teeth not forming a bicusp; cheliceral movable finger with five dorsal teeth; pedipalp chela fixed and movable fingers each with six imbricated subrows of denticles in median denticle row, terminal subrow very short, comprising single denticle; prolateral pedal spurs present on all legs.

RELATIONSHIPS: The trichobothrial pattern of T. sissomi is similar to that of its congeners, except that the patellar em group is displaced distally. Typhlochactas sissomi resembles the four troglobitic species of Typhlochactas in possessing four teeth on the cheliceral fixed finger; the two humicolous species each possess only three teeth. As in most species of the genus, the two basal teeth on the cheliceral fixed finger of T. sissomi are clearly separated; the basal teeth are fused, forming a bicusp, in T. granulosus and T. reddelli only. The new species is similar to T. reddelli and T. rhodesi in possessing five dorsal teeth on the cheliceral movable finger, whereas the other species possess either three or four dorsal teeth. As with T. reddelli and the two humicolous species, T. sissomi possesses prolateral pedal spurs, which are absent in the other three troglobites. Finally, T. sissomi displays six subrows of denticles in the median denticle row

Fig. 4. Typhlochactas sissomi , n. sp., subadult $ holotype ( CNAN T-0308 ). A. Carapace, dorsal aspect .

Scale 5 0.5 mm. B. Sternum, genital operculum, pectines and sternite III, ventral aspect. Scale 5 0.5 mm.

Fig. 5. Typhlochactas sissomi , n. sp., subadult $ holotype (CNAN T-0308), dextral pedipalp femur and patella showing distribution of trichobothria. A. Femur, dorsal aspect. B. Patella, dorsoexternal aspect. C. Patella, external aspect. D. Patella, ventrointernal aspect. Scale 5 1 mm.

of both the fixed and movable fingers of the pedipalp chela, as in T. rhodesi , whereas the other species display different numbers and are usually asymmetrical, with one less subrow on the fixed finger than on the movable finger ( Sissom and Cokendolpher, 1998: 287, table 1).

DESCRIPTION: This description is based on the holotype and only known specimen (fig. 2), complete measurements of which are provided in table 2.

Color: Cheliceral manus pale yellow, teeth light brown. Carapace, pedipalps, tergites, and metasoma, straw-colored. Coxosternal region, legs, sternites, and telson vesicle, pale yellow. Telson aculeus reddish-brown.

Chelicerae: Fixed finger with four distinct, separate teeth dorsally; median and basal teeth separate, not forming a bicusp (fig. 3A). Movable finger with five teeth dorsally and strong, prominent serrula ventrally.

Carapace: Carapace surfaces smooth, shiny; posteromedian and posterolateral sulci shallow, broad; anterior margin straight; ocelli absent (fig. 4A).

Pedipalps: Pedipalp femur rounded in crosssection, with poorly defined carinae (fig. 5A); dorsal and internal surfaces sparsely and coarsely granular; ventral and external surfaces smooth. Patella dorsointernal carina well developed and coarsely granular; internomedian carina comprising only a basal granule; dorsoexternal carina weakly developed, smooth; all other carinae obsolete, smooth (fig. 5B–D). Chela manus surfaces smooth proximally, becoming moderately granular medially (fig. 6A–D); dorsomedian, dorsal secondary and ventroexternal carinae weakly granular. Fixed and movable fingers each with six imbricated subrows of denticles in median denticle row; terminal subrow short, comprising one or two denticles (fig. 3B, C).

Trichobothria: Pedipalps orthobothriotaxic Type C. Femur, patella, and chela with three, 19 and 26 trichobothria, respectively. Femur with three dorsal trichobothria (fig. 5A): i, d, e. Patella with 19 trichobothria (fig. 5B–D): three dorsal: d 1 (petite), d 2 (petite), i; two ventral: v 1, v 2; and 14 external: et 1, et 2 (petite), et 3, est, em 1 – em 3, esb 1, esb 2 (petite), eb 1, eb 2 (petite), eb 3 – eb 5. Chela manus with 16 trichobothria (fig. 6), two dorsal: Db (petite), Dt; four ventral: V 1 (petite), V 2 – V 4; and 10 external: Et 1 – Et 3, Et 4 (petite), Et 5 (petite), Est, Esb (petite), Eb 1 – Eb 3. Fixed finger with 10 trichobothria: four dorsal, distributed across proximal two-thirds of finger: dt, dst, dsb, db (petite); four external, equally distributed: et, est, esb (petite), eb; two internal, situated proximally on finger: it, ib (fig. 6A–C).

Legs: Prolateral pedal spurs present. Retrolateral pedal spurs absent. All surfaces covered with scattered transparent microsetae. Basitarsi with fewer setae than telotarsi. Basitarsus I, ventral surface with short rows of closely aligned, distally directed spinules.

Fig. 6. Typhlochactas sissomi , n. sp., subadult $ holotype ( CNAN T-0308 ), dextral pedipalp chela showing distribution of trichobothria. A. Dorsal aspect. B. External aspect. C. Ventrointernal aspect. D. Ventral aspect. Scale 5 1 mm .

Fig. 7. Typhlochactas sissomi , n. sp., subadult $ holotype ( CNAN T-0308 ), metasoma and telson, dorsolateral aspect. Scale 5 1 mm .

TABLE 2 Meristic data for Typhlochactas sissomi , n. sp., subadult $ holotype ( CNAN T-0308 )

Carapace anterior width: 2.05 posterior width: 2.8 length: 2.9

Chelicera length: 1.4 width: 0.7 movable finger length: 0.8 fixed finger length: 0.5

Chela maximum width: 1.8 maximum height: 1.6 length: 1 4.8 length of ventroexternal carina: 2.1 length of movable finger: 2.7 length of fixed finger: 2.2

Patella maximum width: 1.0 maximum height: 1.0 length: 2.5

Femur maximum width: 0.9 maximum height: 1.0 length: 2.5

Pedipalp total length (incl. trochanter): 10.8

Mesosoma total length (tergites): 6.9

Sternite VII width: 2.6 length: 1.55

Metasoma I maximum width: 1.7 maximum height: 1.3 length: 1.2

Metasoma II maximum width: 1.5 maximum height: 1.3 length: 1.5

Metasoma III maximum width: 1.5 maximum height: 1.3 length: 1.6

Metasoma IV maximum width: 1.5 maximum height: 1.3 length: 1.7

Metasoma V maximum width: 1.5 maximum height: 1.3 length: 3.1

Telson maximum width: 1.7 maximum height: 1.5 aculeus length: 0.8 total length: 3.5

Metasoma total length: 2 12.6

Total length pro-+meso-+metasoma: 22.4

Pectines total length: 1.05 length along dentate margin: 0.93 tooth count (left/right): 5/5

1 Measured from base of condyle to tip of fixed finger.

2 Sum of metasomal segments I–V and telson.

Basitarsi, retrolateral surfaces with very short row of tiny spinules distally. Telotarsi, prolateral, and retrolateral margins each with six to eight pairs of large macrosetae, without median row of spinules ventrally. Ungues moderately long; dactyl moderately developed, slightly curved.

Tergites: Surfaces I–VI smooth, shiny (fig. 2A); VII coarsely granular in posterior half, acarinate.

Sternum: Subpentagonal, wider than long posteriorly; longitudinal sulcus shallow, indistinct (fig. 4B). Coxosternal region smooth, asetose.

Genital operculum: Opercula separated, smooth, shiny, asetose. Genital papillae present (fig. 4B).

Pectines: Each pecten with two marginal lamellae, one median lamella, no fulcra, and five teeth (fig. 4B).

Sternites: Surfaces III–VI smooth, shiny, with book lung stigmata (spiracles) very small and round (fig. 4B); VII acarinate.

Metasoma: Metasoma, intercarinal surfaces smooth, shiny (fig. 7). Dorsosubmedian carinae, segments I–IV, moderately developed, coarsely and sparsely granular; V, absent. Dorsolateral carinae, segments I–IV, absent to obsolete, smooth; V, obsolete, sparsely granular. Median lateral carinae, segments I– V, absent. Ventrolateral carinae, segment I, absent; II–IV, obsolete, smooth; V, moderately developed, granular. Ventrosubmedian carinae, segments I–IV, absent. Ventromedian carina, segment V, absent.

Telson: Vesicle relatively large, globose, smooth, with sparse setae ventrally and distally. Aculeus short.

Hemispermatophore: Hemispermatophore unknown (holotype was dissected and no paraxial organs were found).

Remarks: The metasoma of the holotype is separated from the body at the articulation of segments I and II, the left pedipalp chela is crushed, and the posterior margin of the carapace is slightly damaged (fig. 4A). Left leg I was removed and retained at the AMCC for DNA isolation, amplification and sequencing.

DISTRIBUTION: Known only from the type locality (fig. 1).

ECOLOGY: This troglomorphic species was taken from under a stone on the ground surface in a mesophilous forest. The fact that it was not collected inside a cave, taken together with its similar habitus to the two humicolous species, T. mitchelli and T. sylvestris , suggests that it is probably also humicolous.

Figures

Fig. 1. Map of Mexico showing type localities of known species of Typhlochactas Mitchell, 1968: T. sissomi, n. sp. (1); T. rhodesi Mitchell, 1968 (2); T. cavicola Francke, 1986 (3); T. reddelli Mitchell, 1968 (4); T. granulosus Sissom and Cokendolpher, 1998 (5); T. mitchelli Sissom, 1988 (6); T. sylvestris Mitchell and Peck, 1977 (7).