Serianus elongatus, Mahnert, 2014

Mahnert, Volker, 2014, Pseudoscorpions (Arachnida: Pseudoscorpiones) from the Galapagos Islands (Ecuador), Revue suisse de Zoologie 121 (2), pp. 135-210 : 166-168

Serianus elongatus sp. n. Figs 38-42

HOLOTYPE: MHNG; ♀; Isabela: Bahia Elisabeth , in pitfall trap installed in cracks of a recent lava field, 18.-21.IV.1991, leg. Isabella Lavas & P. Oromi.

ETYMOLOGY: The specific name (a Latin adjective) means elongated.

DIAGNOSIS: Chaetotaxy of half-tergites: I-II 1, III-VII 2; pedipalps: femur with 2 dorsal tactile setae, 4.8 times longer than broad (length 0.41 mm), patella 2.9 times, club 2.0 times, hand with pedicel 2.1 times longer than broad, finger 1.5 times longer than hand with pedicel, chela with pedicel 5.2 times, without pedicel 4.9 times longer than broad; leg arolia deeply divided, distinctly longer than smooth claws.

DESCRIPTION: Carapace and pedipalps yellowish brown, tergites broadly divided (separation indistinct due to feeble sclerotization), sternites undivided. Carapace 1.7 times longer than broad, without transverse furrow, anterior margin rounded, posterior margin desclerotized, 4 large eyes, posterior eye close to anterior one, chaetotaxy: 4-4-4-4-2; chaetotaxy of half-tergites: I-II 1, III-VII 2, VIII-IX 3, X 3/4 (1 lateral, 1 submedial tactile seta), XI (total) 7 (4 tactile setae); pleural membranes finely striate, without setae. Manducatory process with 2 marginal setae (one suboral seta), pedipalpal coxa itself smooth, 6 setae, coxae I-II 4, III-IV 3, genital operculum with 4 (2-2) median marginal setae; chaetotaxy of sternites IV-XI: 4 + 1 suprastigmal seta each-4+2x1-3-6-6-6-5-7 (2 lateral and 2 submedial tactile setae)-4 (3 tactile setae), on VI-VIII 2 discal glandular setae in the middle.

Chelicera (Fig. 38) with 4 long, smooth setae on hand, fixed finger with 3 retrorse teeth and two subapical granula, movable finger with a small, two-pointed(?) lobe, a narrow and indistinct lamina exterior present, subgaleal seta short, not reaching end of galea, galea slender, with 2 apical branchlets, serrula exterior with 16 lamellae, rallum with 4 setae (distal seta with 1 tooth).

Pedipalps (Figs 39-40) smooth, trochanter with small dorsal hump, femur with 2 dorsal tactile setae, 4.8 times longer than broad, patella 2.9 times, club 2.0 times, hand with pedicel 2.1 times longer than broad, finger 1.5 times longer than hand with pedicel, chela with pedicel 5.2 times, without pedicel 4.9 times longer than broad; fixed finger with 32 broad, slightly pointed teeth, movable finger with 23 broad and flattened teeth (only 8 distal ones with small cusp); trichobothria (Fig. 40): 7 placed in basal half on fixed finger, only et near finger end, st of movable finger distinctly distal to sb, which is indistinctly nearer to st than to b; venom duct very short, several modified setae on fixed and movable finger.

Leg I (Fig. 41): femur 2.6 times longer than deep, patella 3.1 times longer than deep and 1.3 times longer than femur, tibia 5.65 times, basitarsus 2.8 times, telotarsus 4.1 times longer than deep, telotarsus 1.3 times longer than basitarsus; leg IV (Fig. 42): femur+patella 4.5 times longer than deep, tibia 6.3 times, basitarsus 2.5 times, telotarsus 4.3 times longer than deep and 1.5 times longer than basitarsus, basitarsus with

FIGS 38-43

Serianus elongatus sp. n., ♀ holotype (38-42), S. galapagoensis Beier, 1978 (43). (38) Right chelicera, with rallum enlarged. (39) Left pedipalp. (40) Trichobothrial pattern. (41) Leg I. (42) Leg IV. (43) Trichobothrial pattern of 3 (right chela) (a), of 3 (left chela) (from Pinta) (b), of tritonymph (c), of deutonymph (d). Scale units 0.1 mm.

a basal tactile seta (TS=0.26), chaetotaxy: TS+1/1/1; arolia divided, distinctly longer than smooth claws, divided at level of claw end.

MEASUREMENTS: Total length 2.17. Carapace 0.45/0.27. Pedipalps: trochanter 0.20/0.09, femur 0.41/0.09, patella 0.31/0.11, pedicel 0.09, hand with pedicel 0.28/0.14, pedicel 0.03, finger-length 0.43, chelal length with pedicel 0.70. Leg I: femur 0.13/0.05, patella 0.17/0.06, tibia 0.20/0.04, basitarsus 0.09/0.03, telotarsus 0.11/0.03; leg IV: femur+patella 0.39/0.09, tibia 0.30/0.05, basitarsus 0.09/0.04, telotarsus 0.14/0.03.

REMARKS: 18 species of this genus are recorded mainly from northern and southern America, but also from Algeria (1), Iran (1) and the Solomon Islands (1). The new species differs from all other species of the genus by its slender pedipalps (e.g. pedipalpal femur more than 4.5 times, chela with pedicel more than 5.0 times longer than broad) and legs (e.g. femur+patella of leg IV 4.5 times longer than deep). Its trichobothrial pattern is also particular within the genus, trichobothrium it being placed halfway between ist and est, which is near the middle of the fixed finger, trichobothrium st being distinctly distal of sb (as opposed to lying above sb) on the movable finger. Differential characters are summarized in the identification key.

The position of st, above or distal to sb, was tentatively used by Mahnert (1988) to separate the genera Garypinus Daday, 1888 and Serianus Chamberlin, 1930 , but this was subsequently found to be unreliable as a generic character since it shows some variability, even in a single individual (e.g. in Serianus galapagoensis ).

The new species might represent an element of the fauna of lava tubes or of the mesovoid shallow substratum (MSS).