Lathys nielseni ( Schenkel, 1932 )

Marusik, Yuri, Koponen, Seppo & Fritzén, Niclas, 2009, On two sibling Lathys species (Araneae, Dictynidae) from northern Europe, ZooKeys 16 (16), pp. 181-195 : 189-194

Lathys nielseni ( Schenkel, 1932)

Figs 4-6 , 10-12 , 17-19 , 23-25 , 28-32

Altella n. Schenkel, 1932: 206, f. 1 (D ♀).

L. humilis: Lehtinen 1967: 242 , f. 264 (♁). Misidentification

L. bifoveolatus Miller, 1971: 71 , pl. IV, f. 3 (D ♀).

L. humilis: Palmgren 1977: 22 , f. 4.20-24 (♁ ♀). Misidentification.

L. n.: Thaler 1981: 126, f. 74-76, 80-84 (♁ ♀).

L. humilis: Hu 1984: 60 , f. 55.1-2 (♀). Misidentification, seems to refer to L. nielseni .

L. n.: Roberts 1987: 170, f. 88a (♁ ♀).

L. n.: Heimer and Nentwig 1991: 380, f. 985 (♁ ♀).

L. n.: Roberts 1995: 88, f. (♁ ♀).

L. n.: Roberts 1998: 90, f. (♁ ♀).

L. n.: Almquist 2006: 320, f. 281a-f (♁ ♀).

L. humilis: Zhu 1985: 58 , f. 48a-c (♁). Misidentification, seems to refer to L. nielseni or L. annulata .

L. humilis: Song et al. 1999: 364 , f. 215N (♁). Misidentification, seems to refer to L. nielseni or L. annulata .

L. humilis: Song et al. 2001: 287 , f. 181A-B (♁). Misidentification, seems to refer to L. nielseni or L. annulata .

Note: some of the references to L. humilis may refer to this species.

Material examined. FINLAND: Åland Isl., Geta, Getaberget : 6♁, 27♀, 33 juv. ( ZMT /ARA28251), lichenous rocks, 24.05.1975 (P.T. Lehtinen) ; Humppila, Rantakallio : 1♀ ( ZMT), 28.06.1962 (P.T. Lehtinen) ; Parainen, Mustfinnö : 1♁ ( MZT), forest, 4.06.1968 (S. Koponen) ; same locality: 1♁, 15♀ ( ZMT), Vaccinium - type forest

(P.T. Lehtinen); same locality: 1♁, 25♀ ( ZMT), among moss in forest, 14.06.1966 (M. Saaristo); Turku, Kärsämäki, Pomponrahka: 5♀ ( ZMT), among Cladonia , 29.03.1967 (M. Saaristo); Dragsŋärd, Purunpää: 1♁ ( ZMT), 6.06- 20.07.1971 (P.T. Lehtinen); Rymättylä, Ruotsalainen: 1♀ ( ZMT), 10.07.1971 (P.T. Lehtinen); Nauvo, Seili: 1♀ ( ZMT), lichenous rock, 1- 30.10.1967 (P. Häkkilä); Somero, Ruunala: 1♁ ( ZMT), 1974-1975 (H. Hippa and R. Mannila); Virrat, Patalankylä, Yli-Havankajärvi: 1 juv. ( ZMT), 11.07.1972 (P.T. Lehtinen); Turku, Ruissalo: 1♀ ( ZMT), 1968 (P.T. Lehtinen); Pori, Yyteri: 1♀ ( ZMT), Elymus dyne, 14.10. 1961 (P.T. Lehtinen); Tuusula, Ruotsinkylä: 6♁, 15♀, 5 juv. ( ZMH), Calluna - type forest, 1962-1965 (V. Huhta); Mäntyharju, Hietaniemi, Mäkelä: 2♁, 2♀ ( ZMH), Vaccinium - type pine forest among Pleurozium , 29.05.1966 (P. Palmgren); Hanko, Tvärminne by: 9♁, 4♀, 5 juv. ( ZMH), Calluna - type pine forest among Cladonia and Hylocomium schreberi , 1.06.1962 (P. Palmgren); same locality and habitat: 5♀, 16 juv. ( ZMH), 8.08.1964 (P. Palmgren); 1♀ ( ZMH), Dragsŋärd, Högholmen: among litter in Myrtillus - type forest, 5.06.2006 (I. Österblad); 1♀ ( ZMH), Hanko, Lappohja, Högsand: 1♀, pitfall-trap, sandy shore, edge of dry pine forest, 19.07- 9.08.2004 (N.R. Fritzén); Kuusamo, Rukajärvi, Rukatunturi: 4♀, 15 juv. ( ZMT), 10.07.1961 (P.T. Lehtinen). RUSSIA: 2♁, 3♀

( ZMMU), Bashkortostan, Ilmenski Reserve, 29.05.1959 and 8.06.1959, (Stebaev). 2♁ 7♀ [ARAN.SIB 117, MZT] Novosibirsk Area, Borovoye, 16.6.1983 (H. Hippa).

Description. Measurements (Finnish specimens). Male. Total length 1.8; carapace 0.89 long, 0.69 wide, 0.42 high; chelicerae 0.53 long. Variation (n=3): total length 1.7-1.9; carapace 0.88-0.90 long, 0.68-0.71 wide, 0.39-0.45 high; chelicerae 0.49-0.63 long.

Length of leg segments:
	femur	patella	tibia	metatarsus	tarsus	total
I	0.81	0.29	0.72	0.63	0.40	2.85
II	0.70	0.27	0.52	0.50	0.35	2.32
III	0.57	0.23	0.37	0.40	0.29	1.87
IV	0.65	0.25	0.50	0.52	0.28	2.20

Female. Total length 1.8; carapace 0.78 long, 0.62 wide, 0.39 high; chelicerae 0.33 long. Variation (n=3): total length 1.6-2.3; carapace 0.75-0.86 long, 0.58-0.65 wide, 0.37-0.40 high; chelicerae 0.26-0.36 long.

Length of leg segments:
	femur	patella	tibia	metatarsus	tarsus	total
I	0.61	0.26	0.47	0.40	0.28	2.01
II	0.53	0.25	0.34	0.34	0.26	1.71
III	0.42	0.24	0.28	0.29	0.21	1.44
IV	0.55	0.23	0.40	0.41	0.23	1.82

Colouration. Carapace in both sexes without distinct pattern, although dark stripes distinguish the cephalic area from the thoracic region. Abdomen with distinct pattern consisting of brownish pigment: long median stripe with transverse arms. Legs without annulations.

Copulatory organs. Male palp ( Figs 10-12 , 17-19 ) with patellar apophysis, tibia with three apophyses (retrolateral dorsal, retroventral and retrolateral (or intermediate) that fix (lock) terminal part of conductor. Conductor very long with two arms. Upper arm coiled, lower part spine-like and slightly twisted. Epigyne as in Figs 23 , 28-32 , with indistinct epigynal fovea and distinct round copulatory openings. Spermathecae egg-shaped. Insemination ducts long with each duct having a vertical and a horizontal loop. First duct turned downwards and then upwards.

Diagnosis. L. nielseni can be easily distinguished from L. humilis and L. annulata by lacking white guanine spots on the abdomen ( Figs 4-6 ). The epigyne of L. nielseni resembles that of L. annulata . The two species can be separated by the shape of the receptacula (egg-shaped in L. nielseni and rounded in L. annulata ) and the longer insemination ducts in the Japanese species. In addition to colour pattern, males of this species can be separated from the European L. humilis by the different shapes of the patellar and tibial apophyses (cf. Figs 13-16 and 17-19 ), the thinner tip of the conductor and the absence of leg annulations (cf. Figs 1, 4 ). The females of the two species can be separated by the shape of the fovea (distinct margins and septum in L. humilis , no distinct margins and septum in L. nielseni ), the shape of the spermathecae and the length and the course of the insemination ducts (cf. Figs 20, 23 , 26-30 ).

Distribution. It seems that this species has a trans-Palaearctic range and is distributed from the UK to Shandong ( China) and possibly to Taiwan. Within Europe, this species has been reported from Austria, Belorus, the Czech Republic, Great Britain, Germany, Slovakia, Sweden and Switzerland ( Helsdingen 2007). In addition, L. nielseni is also known from the St. Petersburg Area and the southern Urals in Russia. The easternmost proven record of this species lies in the Novosibirsk Area (ca 85°E). The northernmost records are from Finland (where the species is often found up to 63°N) and Kuusamo, 66°10’N ( Map 1 ). A comparison of figures of the epigyne ( Figs 31-32 ) made from Finnish and Shandong specimens (identified by Hu 1984 as L. humilis ) leaves no doubt that the Chinese specimens belong to L. nielseni . Other records from eastern China based on males may also refer either to L. nielseni or L. annulata (known exclusively from females). The identity of L. humilis from Gansu ( Schenkel 1936) remains unclear. Figures of the epigyne made by Schenkel are dissimilar to those of both L. humilis and L. nielseni . The specimen stored in the Swedish Museum of Natural History, Stockholm, lacks the epigyne and the abdominal pattern is indistinct due to bleaching.

Habitats. Thaler (1981) reported L. nielseni from warm pine wood steppe (as high as 1500 m a.s.l.), and Buchar and Růžička (2002) mentioned that it occurs within moss and lichens in pine forests (at 400 m). In England this species occurs in moist places at ground level on heathland, under stones or among damp, dead Molinia caerulea litter between the tussocks ( Harvey et al. 2002). Almquist (2006) reported the species from dune heaths. In Finland it has been collected mainly from dry habitats, among litter, moss and lichens, also on sand dunes with Elymus . It seems that this species occurs only in litter, while the sibling L. humilis inhabits bushes and trees, and is found in litter occasionally.

Discussion. The taxonomy of Lathys remains poorly and improperly studied in several respects. The limits of this genus are unclear ( Lathys insulana Ono, 2003 seems to belong to Argenna or an undescribed genus; several Nearctic species appear to be distantly related to L. humilis ). Scotolathys , which has long been considered a synonym of Lathys , was recently revalidated ( Marusik et al. 2009). Many Lathys species remain unstudied since their original description, with many species known only from one sex. Many species appear to have been incorrectly synonymised with L. stigmatisata . Only a few species have been illustrated adequately.

One of the reasons why the genus has been studied unsatisfactorily is a lack of developed species criteria. For example, in his revision, Lehtinen (1967) paid attention to the tip of the conductor, which is very similar in many species, or the structure of the epigynal fovea (also similar in many distantly related species) (P.T. Lehtinen pers. comm.). The species criteria were poorly defined because the conformation of the male

palp was unknown until recently. The first detailed and correct figures of the Lathys male palpal tibia were published by Thaler (1981) and the structure of the bulbus was shown for the first time in 2006 ( Marusik et al. 2006).

Figures

Map 1. Distribution of Lathys humilis (dot) and L. nielseni (square). A square and a circle refer to areas where both species have been found. Some dots and two squares (Germany, Switzerland) refer to state records. An open dot and square refer to a questionable record. Diamonds refer to doubtful records of L. humilis that may relate either to L. nielseni or L. annulata. Specimens from localities east of the broken line have been studied by us (except for questionable records).

Figures 1-6. Habitus and pattern of Lathys humilis (1-3) and L. nielseni (4-6) 1, 4 male, dorsal 2-3, 5-6 female, dorsal 1-2 from Crimea 3 from Azerbaijan 4-5 from Finland 6 from Ural.

Figures 7-12. Male palp of Lathys humilis (7-9, from Crimea) and L. nielseni (10-12, from Finland) 7, 10 ventral 8, 11 retrolateral 9 bulbus, retrolateral 12 bulbus, dorsal 12 after Marusik et al. (2009).

Figures 13-19. Male palp of Lathys humilis (13-16 from Crimea) and L. nielseni (17-19 from Finland) 13, 17 retrolateral 14, 18 ventral 15-16, 19 patella, tibia and base of cymbium, retrolateral-dorsal, different turns 13, 15 after Marusik et al. (2009). Scale = 0.1 mm if not otherwise indicated.

Figures 20-25. Epigyne and male chelicera of Lathys humilis (20-22 from Crimea) and L. nielseni (23- 25 from Finland) 20, 23 epigyne, ventral 21, 24 frontal 22, 25 inner 20 from Azerbaijan 21-22 – from Crimea. Scale = 0.1 mm.

Figures 26-32. Epigyne of Lathys humilis (26-27) and L. nielseni (28-32) 26, 28-29 digital photograph of epigyne, ventral 27, 30 epigyne after maceration, ventral 31-32 epigyne, dorsal 26-27 from Crimea 28, 30-31 from Finland 29 from Ural 26 after Marusik et al. (2009) 32 after Hu (1984). Scale = 0.1 mm.