Typhloroncus guatemalensis, Viana & Ferreira, 2019

Viana, Ana Clara M. & Ferreira, Rodrigo L., 2019, A new troglobitic species of Typhloroncus (Arachnida: Pseudoscorpiones: Ideoroncidae) from Guatemala, Zootaxa 4576 (2), pp. 288-300 : 289-295

Typhloroncus guatemalensis sp. n.

( Figs 1–14 )

Material examined. Holotype female ( ISLA 50051), Guatemala , Alta Verapaz , Gruta de Lanquín, Lanquín (15°34ʹ 49.5ʺN, 89°59ʹ 26.1ʺW), 21 June 2017, leg. R.L. Ferreira. Paratype female ( ISLA 50052), same locality, 24 June 2017, leg. R.L. Ferreira.

Etymology. The specific epithet guatemalensis is an adjective that refers to the country where the species was found, Guatemala.

Diagnosis. Differing from the other members of genus Typhloroncus by the following combination of characters: eyes absent; epistome low and triangular, apically rounded; distinct transverse furrow present near posterior margin of carapace; appendages slender and elongate (e.g. palpal femur 7.4–7.8, palpal patella 6.0, chela with pedicel 7.5–7.6 times longer than broad); 20–22 trichobothria on fixed chelal finger and hand; fixed chelal teeth irregular, with varied morphology (retrorse, flat-topped and rounded teeth); movable chelal teeth also irregular, with varied morphology (retrorse, flat-topped and obsolescent); chelal teeth of both fingers gradually decreasing in size from distal to proximal; subterminal setae short and acuminate; highly modified ventrodistal setae on telotarsus of all legs.

Description of adults (holotype, followed by paratype in square brackets, when different). Troglomorphic habitus ( Figs 1–3 ). Palps, carapace, chelicerae, coxae and first tergites light brown, legs yellowish brown; other parts of body pale yellowish brown. Vestitural setae smooth, long and acuminate.

Carapace ( Figs 4–5 ). 1.5 times longer than broad; anterior margin distinctly sclerotized, with a low, triangular epistome, apically rounded; anterior margin of carapace becoming slightly concave towards mid-region; eyes absent; surface distinctly reticulate ( Fig. 5 ), with a finely reticulate transverse band near posterior margin; a distinct transverse furrow near posterior margin; 6 lyrifissures present, 2 near anterior margin (large), 2 near middle of carapace on right side, and 2 near posterior margin; 14 setae (4 on anterior margin and 2 on posterior margin).

Chelicera ( Figs 6–7 ). Hand with 7 [6] setae; movable finger with 1 subdistal seta; es seta long; galea long and slender; fixed finger with 7 [9] teeth (seventh tooth slightly bifurcate in holotype), followed by 9 [5] proximal denticles [distal part of finger with fine irregularities, but these might be due to wear or fine debris]; movable finger with 10 [7] teeth, the three proximal teeth minute [proximalmost tooth minute], followed by several proximal denticles; rallum ( Fig. 6 ) with 4 blades, each with small unilateral serrations (from the distalmost blade to the basalmost, I–II 7, III 5, IV 4) [each one with small unilateral serrations, except for blade II (I 11, II 8 on distal side and 3 on proximal side, III 8, IV 6)], blades with unequal sizes (I = II> III> IV); serrula exterior with 24 [23] blades, serrula interior with 21 blades; lamina exterior absent.

Tergites. Undivided; surface reticulate; chaetotaxy uniseriate, I–XI 2: 2: 3: 4: 4: 6: 6: 6: 6: 6: 5 [2: 2: 2: 4: 4: 6: 6: 6: 6: 6: 5]. Anal operculum with one pair of dorsal setae. Pleural membranes smoothly, longitudinally striate.

Coxae. Palpal: manducatory process with 2 long, acuminate, distal setae; rest of palp coxae with 6–8 [7–8] setae; median maxillary lyrifissures subbasally situated; surface reticulate. Pedal coxae chaetotaxy I 6, II 7, III 6–7, IV 7–8 [I 6 ¯7, II 7 ¯8, III 7, IV 7]; lyrifissures present on posterior half of coxae I–IV, situated medially on coxae I and II, laterally displaced and near foramen margin on coxae III and IV; surface reticulate.

Genital operculum of female. 10 [7] minute setae situated on posterior margin of sternite II; surface reticulate; 3 [2] lyrifissures present medially. Gonosac large, with scattered pores. Median and lateral cribrate plates not observed.

Female sternites. Chaetotaxy III–XI (1) 4 (1): (1) 6 (1): 10: 11: 11: 10: 11: 10: 4 [(1) 8 (1): (1) 6 (1): 10: 12: 12: 11: 12: 11: 4]. Anal operculum with one pair of ventral setae; anterior margin closely abutting posterior margin of sternite X. Surfaces reticulate.

Palp ( Figs 8–11 ). Trochanter mostly reticulate, except for the retrolateral face, which is scaly. Patella slightly reticulate, almost smooth. Femur scaly distally, gradually becoming reticulate proximally. Chelae mostly smooth, except hand dorsum and most of bases of fingers finely granulate. Fixed finger and hand with 21–22 [20] trichobothria; movable finger slightly shorter than fixed finger, with 10 trichobothria. Trichobothrial pattern ( Fig. 8 ): eb, esb and isb not distributed in a straight row at base of finger, eb proximad to esb and isb; eb region with 1 trichobothrium; ib region with 4 trichobothria (the three basalmost ones isolated on a small dorsal eminence); ist region with 6–7 [5] trichobothria; est region with 6 trichobothria; sb not dorsally displaced relative to st; t region reaching level of est region. Venom apparatus present in both fingers; nodus ramosus slightly distal relative to est region in fixed finger and within t region in movable finger. Fixed finger with 98 [94] irregular teeth, the 14 [8] distalmost teeth cusped and retrorse, thereafter teeth flat-topped ( Fig. 11 ), the 8 [7] proximalmost teeth low and rounded; teeth gradually decreasing in size from distal to proximal. Movable finger with 91 irregular teeth, the 14 [16] distalmost teeth cusped and retrorse ( Fig. 9 ), thereafter teeth flat-topped, the 7 [8] proximalmost teeth extremely low, flat and obsolescent; teeth gradually decreasing in size from distal to proximal.

Legs ( Figs 12–14 ). Subterminal setae short and acuminate, without rami. Telotarsal segments with a few lanceolate ventrodistal setae ( Fig. 12 ), which are darker and longitudinally striate in distal half. Basitarsi and telotarsi with prominent dorsal setae, but no obvious tactile setae. Arolia not divided and shorter than claws, with ventral hooked process; claws smooth.

Measurements and proportions as in Table 1.

Figures

FIGURES 1‒3. Typhloroncus guatemalensis sp. n. 1, habitus of paratype, scale bar 2 mm; 2, live paratype in natural habitat; 3, live holotype in natural habitat.

FIGURES 4‒7. Typhloroncus guatemalensis sp. n. 4, holotype carapace, showing distribution of setae and lyrifissures (most hairs missing), scale bar 0.5 mm; 5, detail of holotype carapace, showing reticulated surface, scale bar 0.25 mm; 6, left cheliceral rallum of paratype, scale bar 0.125 mm; 7, left chelicera of paratype, lateral (slightly ventral) view, scale bar 0.5 mm.

FIGURES 8‒11. Typhloroncus guatemalensis sp. n. 8, left chela of holotype, showing trichobothrial pattern (regions indicated by ellipses) and nodus ramosus, antiaxial view, scale bar 2 mm; 9, detail of left movable chelal finger of holotype, showing distal retrorse teeth and nodus ramosus, antiaxial view, scale bar 0.25 mm; 10, left palp, minus chela, of paratype, dorsal view, scale bar 2 mm; 11, detail of left fixed chelal finger of holotype, showing medial flat-topped teeth and nodus ramosus, antiaxial view, scale bar 0.25 mm.

FIGURES 12‒14. Typhloroncus guatemalensis sp. n. 12, end of telotarsus of left leg IV of holotype, showing modified ventrodistal setae, scale bar 0.5 mm; 13, left leg IV of holotype, scale bar 2 mm; 14, left leg I of paratype, scale bar 2 mm.