Pachygnatha amurensis Strand, 1907

Marusik, Yuri M., Azarkina, Galina N. & Omelko, Mikhail M., 2015, Redescription and a new synonym of the spider Pachygnatha amurensis Strand, 1907 (Araneae, Tetragnathidae, Tetragnathinae), Zootaxa 4007 (1), pp. 126-130 : 126-129

Pachygnatha amurensis Strand, 1907

Figs 1‒20

Pachygnatha amurensis Strand, 1907: 147 (♂), holotype male from environs of Blagoveshchensk (Zoological Museum, Hamburg, examined).

Dischiriognatha cf. tenera Karsch, 1879 : Marusik & Koponen 2000: 65.

Pachygnatha gaoi Zhu, Song & Zhang, 2003: 99 ‒101, 335‒336, f. 44A‒G, 45A‒F (♂♀). New Synonymy

Pachygnatha tenera: Seyfulina 2006: 276 (misidentification).

Material examined. RUSSIA, Amur Area: 1♂ 8♀ ( IBPN), near Arkhara Town, c. 49°25'N, 130°04'E, litter, meadow, 12.08.1983 ( Y.M. Marusik); 3♂ 6♀ ( IBPN), Khingan Reserve, Olochi Kordon, peat-bog, 15.08.1983 ( Y.M. Marusik); 2♂ 1♀ ( IBPN) Khingan Reserve, Antonovskoye Forestry, forest opening, multi-herb meadow, litter, 1.08.1983 ( Y.M. Marusik); Khabarovsk Province: 1♀ ( IBPN), env. of Khabarovsk City, near Bychikha Vill., Bolshekhekhtsyrski Reserve, 48°17.5'N, 134°49.7'E, tall grass with moist ground litter, 11.09.2005 ( Y.M. Marusik); Maritime Province: 1♀ ( ZMHU) "Mantshurien, Nikolsk-Ussurijskij" [=Ussuriysk, c. 43°48'N, 131°57'E], 19.10.1910 (A. Luther); 1♂ 2♀ ( IBPN), Vladivostok, Akademgorodok, forest-park, 30.09.1997 ( Y.M. Marusik); 1♀ ( ZMMU), near Malyshevskoye Village, 3.04.1960 (Soldatov). CHINA: photograph of palp of paratype ♂ of P. gaoi ( HUB), Jilin Province, Jiʼan County (41°06′N, 126°12′E), July 15, 1988 (Jiuchun Gao).

Diagnosis. Only four small sized Pachygnatha species are known in the Russian Far East: P. amurensis , P. degeeri Sundevall, 1830 , P. listeri Sundevall, 1830 and P. quadrimaculata (Bösenberg & Strand, 1906) . Pachygnatha amurensis differs from P. degeeri and P. listeri by having an elongate carapace with a length/width ratio over 1.5, contra 1.3 in P. degeeri and P. listeri , a distinct carapace pattern with darker edges and a median longitudinal line ( Figs 1, 5‒7 ), and in the shape of the copulatory organs. Pachygnatha amurensis also differs from P. quadrimaculata by having dark chelicerae ( Figs 1‒2, 5‒7 ; light in P. quadrimaculata ), lateral wide bands of carapace lacking in P. quadrimaculata ( Figs 1, 5‒7 ) and reticulated abdominal pattern (cf Figs 6‒7 and fig. 46A in Zhu et al. 2003), a small terminal retrolateral tooth on male chelicerae (large in P. quadrimaculata , cf. Figs 2, 4 and figs 47A‒C in Zhu et al. 2003), strongly sclerotised book-lungs spiracles in female with a pair of sigillae between them (sigillae lacking, spiracles weakly sclerotized in P. quadrimaculata cf. Fig. 19 and fig. 46I in Zhu et al. 2003) and tapering conductor and paracymbium (not tapering in P. quadrimaculata Figs 11‒18 and figs D,F in Zhu et al. 2003).

Comments. This species is well described both in Chinese and in English, well illustrated by Zhu et al. (2003: 99‒101, 335‒336), therefore we do not repeat the written description. Although the species was well illustrated some details of the structure of the male palp were not shown. The apical part of paracymbium is gradually tapering and its tip slightly bent and sharply pointed and looks like claw (Cl, Figs 12, 18 ). The tip of conductor was also not properly illustrated and shown sharply pointed and having one arm like in Fig. 15 . In high magnification ( Fig. 17 ) it is clear that the tip of the conductor is bifurcated and has two arms. In addition, there is a small outgrowth (So) on the retrolateral side of the conductor.

Distribution ( Fig. 21 ). Pachygnatha amurensis has a relatively small range and is restricted to the eastern part of the Amur River basin. It is known from Blagoveshchensk (northernmost locality) to Khabarovsk and from Ji'an County in Jilin (southernmost locality) to Vladivostok. It is very likely that this species also occurs in North Korea and Heilongjiang Province of China. The type localities of P. gaoi and P. amurensis lie on the border with North Korea and Heilongjiang respectively.

Figures

FIGURE 21. Distribution records of Pachygnatha amurensis: square, type locality of P. amurensis; diamond, type locality of P. gaoi; filled circle, material examined; open circle, literature records.

FIGURES 1 ‒ 10. Somatic characters of Pachygnatha amurensis male (1 ‒ 4) and female (5 ‒ 10). 1, 5, habitus, lateral; 2, 4, 8 ‒ 9, chelicera retro-ventral; 6, habitus, dorsal; 7 cephalothorax, dorsal; 3, 10, chelicera, anterior. Scale bars: 1, 5 ‒ 6 0.5 mm; 2 ‒ 4, 7 ‒ 10, 0.2 mm.

FIGURES 11 ‒ 20. Copulatory organs of Pachygnatha amurensis. 11 ‒ 18, male palp; 19 ‒ 20, female copulatory organ. 11, ventral; 12, retrolateral; 13, 15, from above; 14, prolateral; 16, conductor and embolus, ventral; 17, conductor and embolus, from above; 19, genital area, ventral; 20, vulva, dorsal. Abbreviations: Cl, claw-like outgrowth of paracymbium; So, outgrowth of conductor. Scale bars: 11, 14, 0.2 mm; 15 ‒ 16, 0.1 mm.