Lusoblothrus Zaragoza & Reboleira, 2012

Reboleira, Ana Sofia P. S., Zaragoza, Juan A., Gonçalves, Fernando & Oromí, Pedro, 2012, Lusoblothrus, a new syarinid pseudoscorpion genus (Arachnida) from Portugal, occupying an isolated position within the Holarctic fauna, Zootaxa 3544, pp. 52-62 : 54-55

Lusoblothrus Zaragoza & Reboleira gen. nov.

Type species. Lusoblothrus aenigmaticus Zaragoza & Reboleira sp. nov.

Etymology. From the adjective luso (late Latin prefix), derived from Lusitania , the old Roman name for modern Portugal, and blothrus, often used for hypogean pseudoscorpion genera of the superfamily Neobisioidea ; gender masculine.

Diagnosis. Syarinidae with elongate opisthosoma. Carapace smooth, with tiny epistome, eyes absent. Apex of pedipalpal coxa triangular, with two setae. Chelicera with five setae on hand; galea simple; rallum with five blades, most of them unilaterally serrate on anterior face, distalmost blade bent to one side and broadened, bearing tiny medial denticulation. Pedipalps with femur and patella granulate, chela smooth (except for pedicel); patella with marked convexity on the antiaxial face. Chela with eight trichobothria on the hand and fixed finger and four trichobothria on movable finger; trichobothria isb -esb -eb situated in distal portion of hand, ib at the base of the fixed finger, trichobothrium it distinctly proximal to et; trichobothrium sb not forming a group with st and t, the latter bent backward and not lanceolate. Stigmata III and IV each with two microsetae; segments X–XI well developed and normal in size. Junction between femur and patella of leg IV perpendicular, patella distinctly longer than femur, tarsal unguitractor plate with spurs on antiaxial face, arolia entire and distinctly longer than the claws on all four legs.

Remarks. Following Zaragoza’s (2010) key to the subfamilies of Syarinidae , the new genus is assigned to the subfamily Ideobisiinae . This is based on the presence of a well-developed galea on movable cheliceral finger, apex of pedipalpal coxa triangular and with 2 setae, trichobothrium isb on antiaxial face of chelal hand, junction between femur and patella of leg IV perpendicular and subterminal setae of tarsi dentate.

Compared with other genera of the subfamily, Lusoblothrus is easily distinguishable from Alocobisium , Chitrellina , Hadoblothrus , Microcreagrella , Microcreagrina and Nannobisium by the position of trichobothrium ib, located on the fixed chelal finger in the new genus, versus on the dorsal face of the chelal hand. Trichobothrium ib is also located on the fixed chelal finger in the genera Ideobisium , Ideoblothrus and Microblothrus . The genus Microblothrus has a reduced trichobothriotaxy, with only seven trichobothria on the fixed chelal finger and three on the movable finger of the adult, and Ideobisium exhibits a different pattern of the trichobothria esb -eb, which have moved to the antiaxial face of the chelal hand, usually near the middle. From the Holarctic fauna, Syarinus Chamberlin, 1925 (subfamily Syarininae ) and Pararoncus Chamberlin, 1938 (subfamily Chitrellinae ) also have trichobothrium ib on the fixed chelal finger, but in Syarinus it has moved to the paraxial face and the rest of the trichobothriotaxy shows a very different pattern compared with Lusoblothrus ; in Pararoncus the trichobothrial pattern resembles that of members of the family Neobisiidae .

Lusoblothrus shows many similarities with Ideoblothrus . Both genera share the following morphological features: similar pattern of trichobothria ib, isb, esb and eb, with latter three on antiaxial face of hand, proximad of base of fixed finger; pedipalpal femur and patella granulate; form of the rallum; and tarsal arolia distinctly longer than claws. Unfortunately, males of Lusoblothrus are unknown and the genitalia cannot be compared. However, the two genera differ in the following respects: shape of pedipalpal patella; position of trichobothrium sb of movable chelal finger (in a cluster with st -t in Ideoblothrus , between b and st in the new genus); junction between femur and patella in leg IV (slightly oblique in Ideoblothrus , perpendicular in Lusoblothrus ); and the shape of trichobothrium t (short and lanceolate in Ideoblothrus , versus long and acuminate in Lusoblothrus ).

The shape of the hair of trichobothrium t on the movable chelal finger in the Syarinidae was recently discussed by Zaragoza (2010). Muchmore (1982) had pointed out that in most of the syarinid genera the shape of trichobothrium t is short and lanceolate, but also noted that in the European and North African genera it is acuminate, not flattened and only a little shorter than the other trichobothria. Trichobothrium t is bent backwards and aligned quite differently to the other trichobothria in most genera ( Harvey & Edward 2007; Zaragoza 2010). Lusoblothrus has a long, acuminate trichobothrium t, as occurs in most of the European genera ( Arcanobisium Zaragoza, 2010 and Syarinus excepted). Zaragoza (2010) suggested that the non-lanceolate shape of t in the hypogean species could be a neoteny, resembling the shape found in the first nymphal stage of Ideoblothrus woodi Harvey, 1991 described by Harvey & Edward (2007).

The presence of spurs on the tarsal unguitractor plate has not been explicitly mentioned in Syarinidae , but Wagenaar Hummelinck (1948) illustrated this feature on the antiaxial face of leg IV for Ideoblothrus maya (p. 68: figs 26b, c) and I. insularum (p. 74, fig. 29h) and directed anteriorly in I. curazavius (p. 64, fig. 25e, f). Spurs also occur on the antiaxial face of the unguitractor plate of leg IV of Lusoblothrus and Microcreagrella ; in Microcreagrina they are reduced to weak tubercles directed anteriorly (J.A. Zaragoza, pers. obs.). The taxonomic importance of this feature remains unknown.

The arolia of the legs, when mentioned or illustrated in the literature, are shorter than the claws in the majority of syarinid genera. The genera Nannobisium (Mahnert 1979) , Chitrellina ( Muchmore 1996) , Ideoblothrus ( Muchmore 1982; Harvey & Edward 2007) and Lusoblothrus all have the arolia as long as or longer than claws. This has been used as a diagnostic character to separate the genera Ideobisium and Ideoblothrus ( Muchmore 1982) . In the European genera Arcanobisium , Hadoblothrus , Pseudoblothrus Beier, 1931 and Syarinus , the arolia are distinctly shorter than the claws, and shorter or as long as the claws in Microcreagrella and Microcreagrina (e.g. Mahnert 1980, 1993; Schawaller 1987; Zaragoza 2010; J.A. Zaragoza, pers. obs.).

The shape of the cheliceral rallum in Lusoblothrus ( Fig. 8), particularly the distalmost blade that is bent laterally and broadened with tiny medial denticulation, strongly resembles the descriptions and illustrations of Wagenaar Hummelinck (1948) for some Ideoblothrus species : I. curazavius ( Wagenaar Hummelinck, 1948) from the Dutch Antilles, I. insularum (Hoff, 1948) from Puerto Rico and I. maya ( Chamberlin, 1938) from Mexico (Yucatán), as well as those of Harvey & Edward (2007) for five Australian species of Ideoblothrus . This morphology has not been mentioned in other descriptions and the distal blade of the rallum in the previously known European syarinid genera has the same shape as the other blades (J.A. Zaragoza, pers. obs.). However, it is possible that this modified characteristic has been overlooked in some cases and hence it should be verified in other genera.