Porrhomma pygmaeum ( Blackwall, 1834 )

Růžička, Vlastimil, 2018, A review of the spider genus Porrhomma (Araneae, Linyphiidae), Zootaxa 4481 (1), pp. 1-75 : 56

Porrhomma pygmaeum ( Blackwall, 1834)

Figs. 49A–F .

Neriene pygmaea Blackwall, 1834 — Blackwall (1834): p. 52 (descr. ♂ ♀); transferred by Simon (1884).

Erigone barbata Thorell, 1875 — Thorell (1875): p. 89 (descr. ♂); synonymised by Holm (1944).

Porrhomma pygmaeum — Simon (1884): p. 366, Figs. 139–140 (♂ ♀).

Bathyphantes arcticus — Strand (1901): p. 23, Figs. 8a–b (descr. ♂ ♀); preoccupied, replaced by Charitonov (1928); examined and synonymised by Holm (1944).

B. strandi Charitonov, 1928 — Charitonov (1928): p. 56; replacement name for B. arcticus .

P. pygmaeum — Holm (1944): p. 130; synonymy.

Material examined. CZECHIA: Třeboň, 12 May –1 Jul 1977, 1 ♂ 1 ♀ ; Suchdol nad Lužnicí, Dvory nad Lužnicí , 22 May 1989, 39 ♂ 29 ♀ ; Sedlec (distr. Břeclav), Lednické Rybníky Ponds Reserve , 5 May 1974, 1 ♂ 1 ♀ ; Míšov, Padrťský Rybník Pond, 6 Jul 1998, 9 ♀, leg. V. Růžička. Tisá , 14 Jul 1999, 1 Ƌ 1 ♀, leg. J. Hajer ( IECA) . FINLAND: Esbo , 13 May 1951, 1 Ƌ 1 ♀, leg. W. Hackman ( AMNH) . SWEDEN: Uppsala, 29 May 1939, 1 Ƌ 3 ♀, leg . Å. Holm ( AMNH). GREAT BRITAIN: Cairngorm Summit , 30 Jun 1966, 1 Ƌ 1 ♀, leg . J.R. Parker ( AMNH). RUSSIA: Kamchatka Peninsula, Petropavlovsk-Kamchatsky , 17 Sep 1996, 1 ♂ 3 ♀ ; Kurile Islands, Shumshu Island , NW shore, 50°46'N, 156°15'E, 9–13 Sep 1996, 13 Ƌ 17 ♀, leg. Yu. M. Marusik (CYM).

Diagnosis. P. pygmaeum differs from other species by dark brown carapace.

Description. ♀ (from Dvory nad Lužnicí, Czechia, 22 May 1989). Carapace dark brown, 0.62 mm wide, eyes normal, PME–PME = 0.7 ( Fig. 49A ). Abdomen dark gray. Fe I–II with one dorsal spine, Fe I with one prolateral spine. Ti I with one prolateral spine, Ti I–II with one retrolateral spine. Tm Mt I = 0.40, Mt I/CW = 0.85.

Ascending parts of the ducts are S-shaped. Spermathecae are formed behind the ascending part of the ducts ( Figs. 49C–F ). Because of a dark colouration, the epigynum is usually hardly visible.

Ƌ (together with female). Embolus of middle length with a narrow velum. AP has the form of a bird head ( Fig. 49B ).

Variation. Ƌ ♀. Carapace 0.60–0.71 mm wide. Tm Mt I = 0.32–0.45, Mt I/CW = 0.77–0.91 (n = 34).

Ecology. Abundant among leaf litter and detritus, also on bushes and herb vegetation of marshy ponds and river margins, in wet forests.

Global distribution. Eurasia after Helsdingen (2017) and Mikhailov (2013). Japan after Ono et al. (2009), Pakistan after Tanasevitch (2011). See Fig. 50 .

Figures

FIGURE 8. Global distribution of Porrhomma altaica new species.

FIGURE 49. A–F, Porrhomma pygmaeum from Dvory nad Lužnicí, Czechia. A, ♀ carapace, frontal view. B, embolic section. C, epigynum. D–F, vulva, ventral, caudal and dorsal. Scale bars, 0.1 mm.

FIGURE 50. Global distibution of Porrhomma pygmaeum.