Pseudochiridium aff. insulae Hoff, 1964

Schimonsky, Diego Monteiro Von, Bichuette, Maria Elina & Mahnert, Volker, 2014, First record of the family Pseudochiridiidae (Arachnida, Pseudoscorpiones) from continental South America — a Pseudochiridium from a Brazilian cave, Zootaxa 3889 (3), pp. 442-446 : 443-445

Pseudochiridium aff. insulae Hoff, 1964

( Figs 2‒3 )

Material examined. Brazil, Bahia, Lapa da Manga I, São Desidério, 12º22ʹ17ʺ S, 44º59ʹ22ʺ W, 579 m, 05.XI.2008, leg. M.E. Bichuette, T.L.C. Scatolini & D.R. Pedroso: 1♀ ( MZUSP 56004).

Description. Carapace and pedipalps yellowish brown, tergites light brown. Carapace 0.9 times longer than broad, coarsely granular; setae leaf-like, numbering about 40 setae (4 on anterior, 7 on posterior margin); no eyespots or eyes; two distinct transverse furrows, subbasal one closer to posterior margin than to median furrow. Posterior margin of carapace and tergites chevroned (posterior ones more distinctly so than anterior ones). Tergites divided, granular (granules smaller than on carapace), setae leaf-like, chaetotaxy of half-tergites (left/right): 4/4:3/5:6/4:6/6:7/6:7/7:7/7:6/ 6:8/7:7/7:13 (total); XI not visible in dorsal view; manducatory process with 3 short and acute setae, pedipalpal coxa granular, with 8 setae (clavate), coxa I 5, II 8, III 13, IV about 44 setae, coxa IV ( Fig. 3 A) with a long posterior extension (length 0.19 mm, breadth 0.175 mm, length/breadth 1.19); sternite II (anterior genital sternite) with an elongate field of about 15 short, acute setae (along mid-line), chaetotaxy of half-sternites III‒X (left/right): 2/3:4/4:8/8:9/9:9/9:7/7:6/ 6:6(total), sternite XI with a total of 6/7; setae on anterior sternites acute, those on IX‒XI clavate (nearly leaf-like); genitalia not observed. Anal cone with 2 dentate dorsal and 2 acute ventral setae. Pleural membranes striate with acute granula.

Chelicera with 5 smooth setae on hand, is long and thicker than others, es short; fixed finger with 3 retrorse teeth, movable finger with a cone-like subapical lobe, seta near tip and reaching to end of galea; galea divided into two branches, one with a tiny apical fork, the second with 3 apical/subapical teeth and a cone-like branchlet near base; serrula exterior with 14 lamellae; rallum with 3 setae, the anterior one dentate and thicker.

Pedipalps ( Fig. 3 B) coarsely granular, setae short and dentate-clavate; femur abruptly enlarged at base, distally tapering, 3.1 times longer than broad, patella 2.3 times, its club 1.7 times, with a hump-like shape in its basal posterior face, hand with pedicel 1.7 times, chela with pedicel 3.1 times, without pedicel 2.9 times longer than broad, hand with pedicel 1.21 times longer than finger; fixed finger with 25, movable finger with 24 low teeth. Trichobothria ( Fig. 3 C): isb distal to esb, est halfway between eb and et, ist indistinctly closer to est than to et; sb on movable finger halfway between b and st, st distinctly closer to t than to sb. Thin venom ducts present in both fingers, reaching to level of et ( Fig. 3 C).

Leg I: femur 1.3 times longer than deep, patella 1.75 times longer than deep and 1.27 times longer than femur, tibia 2.6 times, tarsus 4.4 times longer than deep; leg IV: femur+patella with oblique suture (strongly marked dorsally), 3.6 times longer than deep, tibia 3.4 times, tarsus 5.2 times longer than deep; arolia undivided, as long as the smooth claws. Tarsi carrot-like shaped, ventral face in distal third with tiny, dense, hispid ornamentation.

Measurements (in mm). Total length 1.16. Carapace (length/breadth) 0.40/0.42. Pedipalps: femur 0.31/0.10, patella 0.26/0.11, hand with pedicel 0.25/0.15, length of pedicel 0.03, movable finger 0.21, of chela with pedicel 0.46. Leg I (length/depth): femur 0.09/0.07, patella 0.11/0.06, tibia 0.13/0.05, tarsus 0.17/0.04; leg IV: femur+patella 0.27/0.07, tibia 0.19/0.06, tarsus 0.20/0.04.

Remarks. The pedipalpal measurements and proportions, and some other taxonomic characters, correspond to those of the type series (holotype ♀, paratype ♂) of Pseudochiridium insulae and the unique specimen of this species recorded from the Dominican Republic ( Judson 2007). However, the female from Brazil differs from the description of P. i ns ul a e ( Hoff 1964) in following characters: higher number of setae on the posterior margin of the carapace (7, versus 4 in P. insulae ) and on the tergites (8- 8-10-12-13-14 …, versus 4-6-6-8-10 … in P. insulae ), and in having the setae on the pedipalps shorter and less clavate than in P. insulae . The cheliceral hand has 5 setae (es short, but obvious) as opposed to only 4 well developed setae (es minute or absent) in insulae (as also seems to be the case in Cuban specimens ( Barba & Barroso 2013); however, the specimen from the Dominican Republic also has 5 well developed setae on the cheliceral hand, es being curved and only slightly shorter than b. The transverse furrows on the carapace are reported to be very poorly marked, with the posterior furrow “nearly obsolete” in insulae ( Hoff 1964) , whereas in the Brazilian specimen they are both evident. Furthermore, a difference seems to exist between P. insulae and the Brazilian specimen in the positions of the trichobothria on movable chelal finger: in P. insulae sb-st-t are equidistant ( Hoff 1964, Fig. 2 ), whereas in the Brazilian specimen st is distinctly nearer to t than to sb. However, the specimen of P. insulae from Dominican Republic shows the same arrangement as the Brazilian specimen. Coxa IV of the female, which is considered an important specific character in Pseudochiridium , seems be more slender in the Brazilian specimen than in P. insulae , but no information on the variability of this character is available. The specimen from the Dominican Republic shows a chaetotaxy of the carapace and tergites nearly identical to that of P. insulae (tergites: 4-4-4-6-6-8…), but it has two evident transverse furrows on the carapace. The two specimens from Cuba ( Barba & Barroso 2013) also possess two distinct transversal furrows, but the chaetotaxy of the tergites (4-6-7-8-10 -10…) approaches the higher numbers observed on the Brazilian specimen.

The hispid ornamentation of the tarsi of the walking legs, whose presence was regarded as a generic character of Pseudochiridium by Judson (2007), is worth considering. In the female from Brazil this ornamentation is only present on the distal third of the tarsi, but the specimen from the Dominican Republic show this spinous ornamentation ventrally and laterally over the entire length of the tarsi. The fossil species P. lindae , also has the hispid ornamentation extending along the whole length of the tarsi of legs I‒IV (M.L.I Judson in litt. 24 Oct. 2014). Barba & Barroso (2013) noted that this ornamentation was present ventrally and laterally on the tarsi of P. insulae from Cuba, but they did not indicate whether it extended for the whole length of the tarsi. Observations of more specimens and species are required to determine whether the extent of the ornamentation might be a useful character for distinguishing species.

Pseudochiridium insulae is known only from two specimens from Florida ( USA), one from Dominican Republic and two from Cuba, all of them presenting more or less the same morphological features. The unique specimen available from the Brazilian cave presents noticeable differences in chaetotaxy and palpal morphology, but also in trichobothriotaxy, morphology of coxa IV and tarsus IV, but we ignore their variability within this species and this caveinhabiting population. More specimens are therefore needed to adequately delimit the Brazilian species morphologically and settle its taxonomic status.

Figures

FIGURE 2. Photograph of Pseudochiridium aff. insulae ♀ from Brazil.

FIGURE 3. Pseudochiridium aff. insulae ♀ from Brazil. A. Coxae III ‒ IV (setae of coxae III and left coxa IV omitted); B. Right pedipalp (femur slightly foreshortened); C. Trichobothrial pattern on chelal fingers. Scale divisions = 0.1 mm.