Lebertia (Pilolebertia) gibbosa Lundblad, 1926

Tyukosova, Valentina, Gerecke, Reinhard, Stur, Elisabeth & Ekrem, Torbjørn, 2022, Disentangling the identity of Lebertia porosa Thor, 1900 using integrative taxonomy (Acari: Hydrachnidia), European Journal of Taxonomy 836 (1), pp. 131-169 : 154-156

Lebertia (Pilolebertia) gibbosa Lundblad, 1926

Fig. 9

Lebertia gibbosa Lundblad, 1926: 206 .

Diagnosis

Small in dimensions of appendages (e.g., palp total L<420, L IV-L-4–6 <260, 290, 260); P-2 short (L 90–105), dorsal margin protruding to form a hump-like edge near insertion of dorsal setae, distoventral seta long (about 110). P-3 (L/H 2.2–2.4) and P-4 (L/H 3.0–3.7) very slender, L ratio P-2/P-3 0.9–1.0, P-3/P-4 0.8–0.9. Mediodistal seta P-3 away from dorsodistal seta (L ratio sectors A/B 1.7–1.8). Ventral seta of P- 4 in distal part, distoventral one close to distoventral segment edge (L ventral sectors 57–67, 24–34, 8–9%).

Material examined

Holotype SWEDEN • ♂, “923. Typ (360) Lebertia gibbosa Lundbl. ♂. Östergötland: Kisa rocken. Vålens tillopp. 28.06.1917, leg. O. Lundblad ”; slide mounted; NHRS.

Other material (in ethanol unless otherwise stated)

NORWAY • 1 ♂; Agder , Farsund , Vanse, stream at Vanse school; 58.10366° N, 6.69373° E; 6 m a.s.l.; 25 Jun. 2020; Torbjørn Ekrem and Thomas Stur Ekrem leg.; kick sample; BOLD specimen ID HYDCA467 ; NTNU-VM 227896 • 1 ♂; Agder , Farsund, Vanse, stream at playground; 58.09846° N, 6.69490° E; 6 m a.s.l.; 25 Jun. 2020; Torbjørn Ekrem and Thomas Stur Ekrem leg.; kick sample; BOLD specimen ID HYDCA569 ; NTNU-VM 227897 • 1 ♂, 2 ♀♀, 1 dn; Agder , Froland , Nidelva, near Blakstad, upstream bridge Frolandsveien, E riverbank; 58.51004° N, 8.64806° E; 40 m a.s.l.; 28 Aug. 2019; Gaute Kjaerstad and Reinhard Gerecke leg.; BOLD specimen ID HYDCA306 , HYDCA 429 , HYDCA454 , HYDCA455 ; NTNU-VM 227882 to 227885 • 2 ♂♂, 2 ♀♀; Agder , Søgne , Søgneelva, upstream bridge close to old Søgne Church; 58.08952° N, 7.83998° E; 2 m a.s.l.; 21 Jun. 2020; Gaute Kjaerstad and Reinhard Gerecke leg.; BOLD specimen ID HYDCA432 (slide mounted), HYDCA433 (slide mounted), HYDCA 462 , HYDCA463 ; NTNU-VM 227886 to 227889 • 1 ♂, 2 ♀♀; same collection data as for preceding; slide mounted; NTNU-VM 227891 to 227893 • 2 ♂♂, 2 ♀♀; same locality as for preceding; 30 Aug. 2019; NTNU-VM 227890 • 1 ♂; Agder , Søgne , Flomdam , Søgneelva upstream bridge near old Søgne church; 58.08962° N, 7.83937° E; 2 m a.s.l.; 30 Aug. 2019; Gaute Kjaerstad and Reinhard Gerecke leg.; BOLD specimen ID HYDCA558 ; NTNU-VM 227894 • 1 ♂; same collection data as for preceding; NTNU-VM 227895 • 1 ♀, 1 dn; Trøndelag , Orkdal , Orklavassdraget, Sagbekken, station 1; 63.24614° N, 9.67573° E; 175 m a.s.l.; 26 Jul. 2018; Gaute Kjaerstad leg.; NTNU-VM 227998 .

Description

Colour in life unknown. Integument with a fine porosity. Coxal field with medial sutures Cx-I slightly longer than medial sutures Cx-II (ratio about 1.2), Cx-II posteromedially forming a narrow, acute angle. Posterior margin of Cx-IV equally rounded or forming an obtuse angle near apodeme in medial sector. Swimming setation: II-L-5 4–5; III-L-4 4–5; III-L-5 7–9; IV-L-4 4–5; IV-L-5 7–9. Chelicera L/H ratio 8.0, basal segment/claw ratio 7.0.

Males

Idiosoma L 1060, coxal shield 740, Cx-I/II mL 190/165. Genital field L/W 190/130, with 34–44 medial setae; Ac-1–3 L 65, 50, 35. Gnathosoma L 200; chelicera basal segment L 270, H 55; claw 60.

Leg measurements (L/H, ratio): I-L-4 121–132/46–48, 2.62–2.86; I-L-5 125–138/37–40, 3.35–3.65; I-L-6 99–125/35–38, 2.81–3.35; IV-L-4 227–240/48–55, 4.36–4.86; IV-L-5 242–260/37–43, 6.12–6.47;

IV-L-6 207–225/40, 5.22–5.63; proportions of segments (L ratio): IV-L-4/5 0.92–0.94, IV-L-4/6 1.07– 1.10, IV-L-5/6 1.15–1.17; IV-L claw L 50.

Palp measurements (L/H, ratio, % total L): P-1 30/43, 0.7, 8; P-2 92–96/60–62, 1.5–1.6, 25; P-3 97– 103/44–45, 2.2–2.3, 27; P-4 112–123/36–38, 3.1–3.3, 32; P-5 33/5, 7,2, 8; proportions of segments (L ratio): P-2/P-3 0.94–0.96, P-2/P-4 0.79–0.82, P-3/P-4 0.83–0.86; distance ratio distal setae P-3 (A/B) 1.67; P-4 ventral sectors 63%, 28%, 9%; palp total L 384.

Females

Idiosoma L 900–1200; coxal shield 720–750; Cx-I/II mL 210–225/170. Genital field L/W 180–190/150, with 18–24 medial setae; Ac-1–3 L 55–60, 55–60, 38–40. Gnathosoma L 210; chelicera basal segment L 210, H 30; claw 30.

Leg measurements (L/H, ratio): I-L-4 145/50, 2.90; I-L-5 150/40, 3.75; I-L-6 130/38, 3.47; IV-L- 4 255/60–65, 3.92–4.25; IV-L-5 273–280/48–55, 4.95–5.89; IV-L-6 240–250/43–45, 5.33–5.88; proportions of segments (L ratio): IV-L-4/5 0.91–0.94, IV-L-4/6 1.02–1.06, IV-L-5/6 1.12–1.14; IV-L claw L 50–55.

Palp measurements (L/H, ratio, % total L): P-1 31–33/43–45, 0.7, 8; P-2 100–103/63–65, 1.6, 24–25; P-3 110–113/48, 2.3–2.4, 27; P-4 130–138/38–39, 3.4–3.7, 32–33; P-5 33/5, 7.2, 8; proportions of segments (L ratio): P-2/P-3 0.91, P-2/P-4 0.73–0.79, P-3/P-4 0.80–0.87; distance ratio distal setae P-3 (A/B) 1.80; P-4 ventral sectors 57–67 %, 24–34 %, 8–9 %; palp total L 410–411.

Remarks

The meagre original description is without measurement data and refers in most details to character states typical for all species of the subgenus Pilolebertia ( Lundblad 1926) . The only diagnostic feature mentioned is the name-giving shape of P-2, elevated to form an obtuse-angled hump. Lundblad’s fig. 5 shows a palp with P-3 having the mediodistal seta approaching the dorsodistal seta (calculated ratio A/B ca 2.0). P-3/-4 slender (L/H ratio 2.1, 2.9), P-3 proportionally long (L ratio P-3/4 0.85).

Lebertia gibbosa fits the characteristics of the porosa -like Lebertia species in the absence of a kink in the distoventral gnathosomal margin, but distinct differences are found in the characteristic, namegiving hump of P-2, the slender palp segments P-3 and P-4, the position of the ventral setae (both in distal half, proximal sector>50%), and the small size of the distal peg seta on P-4. The P-4 size is similar to that in L. inaequalis (Koch, 1837) , and application of the key in Gerecke (2009) is misleading, keying L. gibbosa to L. inaequalis . Lebertia inaequalis agrees with L. gibbosa also in the swimming setation, but differs, in addition to the ventral kink of the gnathosoma, in having a P-2 with its dorsal margin equally curved, not protruding to form a hump, and P-3 with mediodistal seta not, or only slightly, approaching the dorsodistal seta. A comparison with measurements of Norwegian specimens morphologically attributed to L. inaequalis reveals a wide overlap in many dimensions and proportions. The latter differ from L. gibbosa in having a more slender I-L-6 (L/H>3.7), longer IV-L claws (> 55) and a higher P-2/P-3 ratio (> 1.0). DNA barcode data in BOLD indicate that L. inaequalis , similar to what is shown here for L. porosa aggr., represents a species complex with several BINs under this name. Upon taxonomic revisions, we expect that the wide variability for leg proportions of L. inaequalis described by Gerecke (2009) will cover a range of several distinct species.

Before our study, this species was only known from its type locality on the island of Gotland ( Sweden). Our data show a wide distribution in southern Norway, in the north reaching up to southern Trøndelag County (63° N). As this species has been widely overlooked, the full geographical distribution of L. gibbosa cannot be defined without additional research.

Figures

Fig. 9. Lebertia (Pilolebertia) gibbosa Lundblad, 1926, holotype, ♂ (NHRS). A. Venter. B. Palp. C. I-L. D. II-L. E. III-L. F. IV-L. Scale bars = 100 µm.