Feaella (Tetrafeaella) obscura, Novák & Lorenz & Harms, 2020

Novak, Janos, Lorenz, Michelle & Harms, Danilo, 2020, Feaella (Tetrafeaella) obscura sp. nov. - a new pseudoscorpion species from the Maldives (Arachnida, Pseudoscorpiones), and an updated identification key to the subgenus Feaella (Tetrafeaella), Zoosystematics and Evolution 96 (2), pp. 769-779 : 769

publication ID	https://dx.doi.org/10.3897/zse.96.56885
publication LSID	lsid:zoobank.org:pub:4D358991-0404-4FF9-A9BD-0E9288B5E355
persistent identifier	https://treatment.plazi.org/id/C6FF5DD9-BE35-4AEA-A049-3BB24048D9DB
taxon LSID	lsid:zoobank.org:act:C6FF5DD9-BE35-4AEA-A049-3BB24048D9DB
treatment provided by	Zoosystematics and Evolution by Pensoft
scientific name	Feaella (Tetrafeaella) obscura
status	sp. nov.

Treatment

Feaella (Tetrafeaella) obscura sp. nov. Figs 2A-F View Figure 2 , 3A-H View Figure 3 , 4A-F View Figure 4 , 5A-G View Figure 5

Type material.

Holotype female from the Maldives, Kabudu Island (might refer to Kaudu [0°17'N, 73°1'E] or Kandudu Islands [2°19'N, 72°55'E]), June 1984, leg: Győző Horváth. [On the label: Maldives, Kabudu sz., 1984.VII. leg.: Győző Horváth] (HNHM Pseud-2009). Paratypes: 1 male (HNHM Pseud-2010) and 1 female (ZMH-A0003101); all same data as holotype.

Etymology.

The name of the species refers to the obscure evolutionary and geographic origins of the species that is unlikely to have evolved on the young island that is the locus typicus.

Distribution.

Maldive Islands (Fig. 1 View Figure 1 ).

Diagnosis.

A typical Feaella (Tetrafeaella) habitus (Figs 2A, B View Figure 2 , 3A View Figure 3 ) that differs from all the other species of the subgenus by the following combination of characters: with the anteromedian lobes of carapace being closer to each other than to the anterolateral ones; anterolateral pair approximately as broad as anteromedian pair, anteromedian lobes longer. Palpal trochanter with prolateral triangular protuberance, femur very robust (1.70-1.76 ×) with two pronounced triangular process on prolateral corner near base. Chelae are approximately as long as the palpal femora. Chelae with dorsal protuberance at basal third of finger, and a large medial tooth at the base of each fingers. Chelal trichobothriotaxy: esb and est situated on basal third of retrolateral face; ib, isb and ist situated basally; eb and it situated subdistally; dt situated distally; esb midway between est and isb; ist equidistant from est and esb; isb is closer to ib than to ist; on the movable chelal finger t and sb are situated midway between b and st. Pedal coxa I with medioposterior depression (coxal pit), a single primary coxal spine posteriorly; coxa II with 9 secondary spines in males and 8-11 in females. Pleural membrane with a dorsal row of 15 and a ventral row of 14 sclerotised pleural platelets. See detailed differentiation from the most similar species in the Differential diagnosis, and differentiation from all the other species of the subgenus in the key.

Description.

(Holotype female, paratype male and female). Colour and cuticular surface (in alcohol): sclerotised parts reddish-brown, with reticulated cerotegument (Fig. 2A-F View Figure 2 ).

Setae: most vestitural setae short, slightly curved, inconspicuous and acuminate.

Chelicera (Fig. 5A View Figure 5 ): hand with five setae, is and ls adjacent to each other, movable finger with subdistal seta. Galea thick, without rami. Fingers without teeth. Serrula exterior with ca. 16 blades, lamina exterior absent. Rallum absent.

Pedipalps (Figs 2F View Figure 2 , 5B View Figure 5 ): trochanter with prolateral triangular protuberance, femur very robust with two pronounced triangular process on prolateral corner near base, 0.63-0.69/0.37-0.40 (1.70-1.73 ×) in females and 0.51/0.29 (1.76 ×) in male; patella conical, and with two lyrifissures at base, 0.51-0.54/0.18-0.19 (2.83-2.84 ×) in females and 0.41/0.14 (2.93 ×) in male; chela tubular (Figs 3G View Figure 3 , 4A-F View Figure 4 , 5C View Figure 5 ), chela (with pedicel) 0.60-0.61 in females and 0.53 in male, chela (without pedicel) 0.57 in females and 0.50 in male; hand without pedicel and longer than broad. Fixed chelal finger and hand with eight major trichobothria, plus duplex trichobothrium (dt), movable chelal finger with four trichobothria: esb and est situated on basal third of retrolateral face; ib, isb and ist situated basally; eb and it situated subdistally; dt situated distally; esb midway between est and isb; ist equidistant from est and esb; isb is closer to ib than to ist. On the movable chelal finger t and sb are situated midway between b and st (Fig. 5C View Figure 5 ). Venom apparatus absent. Chelal hand very small; retrolateral condyle rounded; with dorsal protuberance at basal third of finger (Fig. 5C View Figure 5 ). Chelal teeth large, retrorse and diastemodentate: fixed finger with two parallel marginal dental line, one with 11 and one with 9 teeth, 9 prolateral and 7 distal teeth in male; 12-13 and 9-13 marginal, 9-10 prolateral and 3-4 distal teeth in females; movable finger with two parallel marginal dental line with 9 + 9, 9 prolateral and 7 distal teeth in male; 12 and 9 marginal, 9-10 prolateral and 6 distal teeth in females; plus a large medial tooth at the base of each finger. Movable chelal finger with several specialised, lanceolate setae midway between t and tip of finger; located in a depression (Fig. 3H View Figure 3 ).

Carapace: anterior margin with four lobes, the anteromedian lobes are closer to each other than to the anterolateral ones; anterolateral pair approximately as broad as anteromedian pair, anteromedian lobes longer (Figs 2D View Figure 2 , 3E View Figure 3 ). Four lobes between eyes. Lateral margins of carapace nearly parallel, slightly widened medially; carapace in females 1.27-1.28 ×, in male 1.24 × longer than broad; with two pairs of eyes situated on tubercles away from anterior carapace margin; all eyes with tapetum; with numerous inconspicuous setae; with a pair of postero-lateral processes; shallow anterior and posterior furrows present. Three slit-like lyrifissures at the level of posterior one-fourth of carapace on each side, and two near posterior base.

Coxal region (Figs 2E View Figure 2 , 3B View Figure 3 ): pedipalpal coxa with strong basal lateral processes; with numerous small setae and 3 acuminate apical setae. Coxa I with medioposterior depression (coxal pit), a single primary coxal spine posteriorly; coxa II with 9 secondary spines in male and 8-11 in females (Fig. 3C View Figure 3 ). Pedipalpal coxa somewhat longer as combined length of leg coxae I-IV.

Legs (Fig. 5D, E View Figure 5 ): claws simple, arolium shorter than claws. Metatarsi and tarsi fused. Each patella with a shallow dorsal depression. Tarsi without tactile setae, vestitural setae short and acuminate. Patellae I and II slightly shorter than femora I and II; patellae III and IV nearly twice as long as femora III and IV.

Abdomen: longer than broad, somewhat ovoid; tergites II-IX and sternites IV-X with distinct median suture lines; tergite XI and sternite XI fused; tergite XII and sternite XII (anal sclerites) strongly sclerotised; most segments with numerous setae; tergite XII and sternite XII with two setae; anal region with raised circular rim (Fig. 3D View Figure 3 ). Setae of sternites II and III longer than vestitural setae. Pleural membrane with a dorsal row of 15 and a ventral row of 14 sclerotised pleural platelets.

Genital region: Female (Figs 3F View Figure 3 , 5F View Figure 5 ): 10 acuminate microsetae on each plate. Male (Fig. 5G View Figure 5 ): 40-45 acuminate microsetae on genital plate. Inner genital structures could not be clearly seen.

Measurements (in mm, ratios in parentheses): Male paratype. Body 1.83. Carapace 0.51/0.41 (1.24 ×). Chelicera 0.19/0.10 (1.9 ×), movable finger 0.085. Palpal femur 0.51/0.29 (1.76 ×), patella 0.41/0.14 (2.93 ×), chela (with pedicel) 0.53/0.13 (4.08 ×), chela (without pedicel) 0.50, hand (with pedicel) 0.15, hand (without pedicel) 0.12, movable finger 0.37. Leg I. trochanter 0.12/0.19 (0.62 ×), femur 0.21/0.06 (3.50 ×), patella 0.18/0.07 (2.57 ×), tibia 0.17/0.06 (2.83 ×), tarsus 0.23/0.05 (4.60 ×). Leg IV. trochanter 0.22/0.12 (1.83 ×), femur 0.16/0.08 (2.00 ×), patella 0.28/0.10 (2.80 ×), tibia 0.32/0.06 (5.33 ×), tarsus 0.32/0.05 (6.4 ×).

Females (holotype, followed by paratype in parentheses and then the ratios also in parentheses). Body 2.16 (2.46). Carapace 0.61/0.48 (0.64/0.50) (1.27-1.28 ×). Chelicera 0.20/0.12 (0.21/0.12) (1.67-1.75 ×), movable finger 0.095 (0.10). Palpal femur 0.63/0.37 (0.69/0.40) (1.70-1.73 ×), patella 0.51/0.18 (0.54/0.19) (2.83-2.84 ×), chela (with pedicel) 0.60/0.16 (0.61/0.16) (3.75-3.81 ×), chela (without pedicel) 0.57 (0.57), hand (with pedicel) 0.16 (0.17), hand (without pedicel) 0.12 (0.10), movable finger 0.40 (0.41). Leg I. trochanter 0.15/0.11 (0.16/0.12) (1.33-1.36 ×), femur 0.24/0.07 (0.27/0.08) (3.38-3.43 ×), patella 0.22/0.08 (0.21/0.09) (2.33-2.75 ×), tibia 0.20/0.07 (0.22/0.07) (2.85-3.14 ×), tarsus 0.22/0.05 (0.22/0.05) (4.4 ×). Leg IV. trochanter 0.26/0.14 (0.27/14) (1.86-1.93 ×), femur 0.18/0.10 (0.19/10) (1.8-1.9 ×), patella 0.36/0.11 (0.37/0.12) (3.08-3.27 ×), tibia 0.42/0.06 (0.44/0.07) (6.29-7.00 ×), tarsus 0.36/0.05 (0.38/0.06) (6.33-7.20 ×).

Differential diagnosis.

Aside from Feaella (T.) obscura there are twelve species of Feaella (Tetrafeaella) : F. (T.) affinis Hirst, 1911 (Seychelles); F. (T.) capensis Beier, 1955, F. (T.) mucronata Tullgren, 1907 and F. (T.) parva Beier, 1947 (all South Africa), F. (T.) indica Chamberlin, 1931 (India and Sri Lanka), F. (T.) leleupi Beier, 1959 (Congo), F. (T.) nana Beier, 1966 comb. nov. (previously treated as a subspecies of capensis but see below), F. (T.) perreti Mahnert, 1982 (Kenya) and the western Australian species F. (T.) anderseni Harvey, 1989, F. (T.) callani Harvey et al., 2016, F. (T.) linetteae Harvey et al., 2016 and F. (T.) tealei Harvey et al., 2016.

Feaella (T.) obscura is most similar in general habitus of carapace and pedipalps and in most characters (see in the key below) to the following species from Africa, India and the Seychelles.

It differs from F. (T.) capensis in having a pronounced and triangular dorsomedial process on the prolateral corner of palpal femur near its base (absent in F. (T.) capensis ), conical shape of the frontal carapace lobes (long and triangular), pleural membrane with a dorsal row of 15 and ventral row of 14 platelets (15 and 15 in F. (T.) capensis ) ( Beier 1955).

Feaella (T.) obscura differs from F. (T.) nana in having a pronounced and triangular dorsomedial process on the prolateral corner of the palpal femur near its base (absent in F. (T.) nana ). Furthermore, in having pleural membrane with a dorsal row of 15 and a ventral row of 14 sclerotised pleural platelets (in F. (T.) nana the number of these are 14 and 14). In Feaella (T.) obscura on fixed chelal finger isb much closer to ib than to ist and these three trichobothria do not form a straight row, and trichobothrium eb situated clearly closer to the fingertip than to ist (in F. (T.) nana isb, ib and ist are equally placed and form a straight row, and eb is situated midway between ist and the finger tip) ( Beier 1966).

The new species differs from F. (T.) indica in having a pronounced and triangular dorsomedial process on the prolateral corner of palpal femur near its base (in F. (T.) indica this process is absent). The chelae of F. (T.) obscura are approximately as long as the palpal femora (in F. (T.) indica these are distinctly shorter than the palpal femora). Furthermore, the palpal femur length/width ratio of F. (T.) obscura is 1.70-1.76 × (this value is 1.90 × in F. (T.) indica ) ( Chamberlin 1931; Beier 1932).

In the case of F. (T.) affinis Hirst, 1911 trichobotria sb and st of movable chelal finger are closer to b than t (in the new species sb and st are situated midway between b and t). Furthermore, in F. (T.) affinis trichobothrium ist of fixed chelal finger is at the level of esb and est is placed distal to them (in F. (T.) obscura , ist is equidistant from est and esb) ( Mahnert 1978).