Genus Syntropis Kraepelin 1900

Syntropis Kraepelin, 1900: 16-17; type species by monotypy Syntropis macrura Kraepelin, 1900; Birula, 1917a: 163; Werner, 1934: 281; Kästner, 1941: 272; Mello Leitão, 1945: 118; Williams, 1969a: 285; Williams, 1974: 15 (part); Stahnke, 1974a: 113-120; 1975: 257-258; Vachon, 1974: 914, 916; Díaz Najera, 1975: 3, 6; Williams, 1980: 47; Sissom, 1990a: 110, 114; Sissom, 1991b: 26; Nenilin & Fet, 1992: 9; Stockwell, 1992: 408; Kovarík, 1998: 146; Beutelspacher, 2000: 55, 70, 152, Lam. IId; Sissom, 2000:526; Ponce Saavedra & Beutelspacher, 2001: 20; Soleglad & Fet, 2003a: 15, 36, 67, 144, 163, figs. 66, 79, 80, D-4, Tabs. 3, 4, 9; Soleglad, Lowe and Fet 2007: 119-136, Fig. 1–37; Tables I, II.

Description.  

Prosoma. –  Anterior carapacial margin weakly concave.

Mesosoma. – Pectinal tooth counts 26-32 in males, 24-31 in females.  All female pectinal teeth similar in size and shape, and with sensorial areas. 

Metasoma. –  Dorsal carinae of segments I-IV with even fine granulation; terminal denticles not distinctly enlarged.  Metasoma I-V with a single ventromedian carina.  Segment V with ventromedian carina linear throughout. 

Chelicerae. –  Ventral margin of the cheliceral movable finger smooth; fixed finger lacking ventral denticles.  Serrula poorly developed distoventrally on movable finger.

Pedipalps. –  Patella:  Inner face with basal tubercles weakly developed; with inner longitudinal carina.  Chelal carinae:  Ventromedian carina absent, but ventral face of chela more or less convex.  All carinae absent to feebly developed. Chela dentition: Terminal denticles moderately large, conically shaped.  Chela fixed finger with primary denticle row divided into six subrows of denticles, these are flanked by six inner accessory denticles.  Chela movable finger with primary denticle row divided into six to seven subrows of denticles (single denticle of apical "row" sometimes missing), these flanked by eight inner accessory denticles.  Chela fingers with distinct white apical caps.  Denticles of denticle row subconical, subserrate. 

Trichobothrial Pattern.  Patella with two ventral trichobothria along ventroexternal carina (the third ventral trichobothrium is positioned on the external face). Chela with four ventral (V) trichobothria.  Chelal trichobothria ib positioned on the fixed finger near the sixth inner accessory denticle of the primary denticle row. Trichobothrium est positioned about equidistant between et and esb. 

Legs. –  Basitarsi and telotarsi without setal combs.  Telotarsi ventrally with a median row of small spinules that are flanked distally by four or more slightly larger spinules.  Ventromedian spinule row flanked laterally by paired setae.

Hemispermatophore. – Mating plug present, with spines on ental process.  Lamellar process a bilobed flange, elevated on distal lamina and positioned on ectal margin. 

Included species. – Syntropis aalbui Soleglad, Lowe and Fet 2007, Syntropis macrura Kraepelin 1900, Syntropis williamsi Soleglad, Lowe and Fet 2007.

Similar taxa. – See Vaejovis C. L. Koch (eusthenura group). 

Remarks. - Syntropis was established as a monotypic genus to accommodate Syntropis macrura, referred to by Williams (1980) as "one of the most interesting North American scorpions."  For decades, the genus was known only from the holotype of Syntropis macrura.  Williams (1969, 1980) reported additional material and provided information on the biology of Syntropis macrura (to which he referred all known specimens). Of Syntropis macrura, Williams (1980) said:

"This species is adapted to volcanic habitats where it utilizes the spaces between fractured rocks for shelter. Most specimens found were on more or less vertical cliffs, often high above the ground. In the Comondu area this species has invaded rock walls built by residents in the bottom of the arroyo to keep goats out of farm lands. It does not generally spend much time in exposed situations, even during nocturnal hours.
Juveniles appear much different from adults. They are uniformly pale yellow and lack the contrasting color markings of adults, their metasoma is not as elongate, and their telson is not elongate.
Some geographical variation was evident. The Comondu populations were very much like those taken on Isla Carmen except that the vesicle of the island population was slightly less hirsute. Other than this, the two populations seemed essentially the same and corresponded with the description of the holotype. Adult specimens taken at the southern end of the Sierra Giganta appeared different from the Comondu population as follows: lighter coloration (perhaps reflecting the general lighter coloration of their habitat); adult males had metasomal segment V 5.2 times longer than wide (instead of 7 times longer); adult females had metasomal segment V 4.0 to 4.3 times longer than wide (instead of 5.2 times longer); pectine teeth of males were 26-28 (not 29-32); pectine teeth of females were 24-26 (not 27-31); vesicle was less elongate and more swollen in both sexes."

Soleglad, Lowe and Fet (2007) studied six specimens of Syntropis from Baja California (one adult female, one large subadult male, and two subadult females from the vicinity of Los Aripes, and one adult female each from Isla del Carmen and the vicinity of Catavina), and compared measurements from these six specimens with Stahnke’s (1965) reported measurements of the S. macrura male type, adjusting for apparent errors in Stahnke’s values for the pedipalp femur and patella, which they reported are too small, by using measurements derived from Stahnke’s (1965: fig. 2) photograph of the male holotype.  They noted that error in Stahnke’s reported values for the pedipalp femur and patella is particularly obvious when looking at the larger photograph (Stahnke, 1965: fig. 1). In that photograph, the femur appears considerably longer than metasoma segment I and longer than segment II, whereas Stahnke’s measurements indicate that the femur is only slightly longer than segment I and shorter than segment II.
Soleglad, Lowe and Fet (ibid.) noted Williams’ (1980) previous observations about specimens of Syntropis taken at the southern end of the Sierra and reported that their four specimens from the vicinity of  Los Aripes comply with all of Williams’ observations, having a relatively stout metasoma and telson vesicle and a relatively stocky femur and patella on the pedipalp (18 to 36% difference in the slenderness of the pedipalp femur and patella from other examined material), an overall light yellow coloration (including the chelal fingers, which are darkly pigmented in other populations), and lower pectinal tooth counts (24–25 in females and 25–26 on the male).
Soleglad, Lowe and Fet (ibid.) further noted that their large adult female specimen from Cataviña also demonstrates significant morphometric differences from S. macrura, having a relatively stocky metasoma and telson, similar to those seen in the Los Aripes specimens. They noted that the Catavina specimen differs from the Los Aripes specimens in having a more slender femur and patella on the pedipalp, more similar to S. macrura.  They noted that the Catavina specimen  exhibits a 28 to 33% difference in the slenderness of metasomal segments III to V and a 17% difference in the slenderness of the telson vesicle from the more slender S. macrura.
Based upon their studies, Soleglad, Lowe and Fet (ibid.) recognized three species in Syntropis:  Syntropis aalbui Soleglad, Lowe and Fet 2007, Syntropis macrura Kraepelin 1900, Syntropis williamsi Soleglad, Lowe and Fet 2007.