Standardized spider (Arachnida, Araneae) inventory of Hankoniemi, Finland.

BACKGROUND: During a field course on spider taxonomy and ecology at the University of Helsinki, the authors had the opportunity to sample four plots with a dual objective of both teaching on field methods, spider identification and behaviour and uncovering the spider diversity patterns found in the southern coastal forests of Hankoniemi, Finland. As an ultimate goal, this field course intended to contribute to a global project that intends to uncover spider diversity patterns worldwide. With that purpose, a set of standardised methods and procedures was followed that allow the comparability of obtained data with numerous other projects being conducted across all continents. NEW INFORMATION: A total of 104 species and 1997 adults was collected. Of these, 41 species (39%) were Linyphiidae and 13 (12%) Theridiidae. All other families had 6 or less species represented. Linyphiidae were also dominant in terms of adult individuals captured, with 1015 (51%), followed by 428 (21%) Lycosidae, 158 (8%) Tetragnathidae and 145 (7%) Theridiidae. All other families had less than 100 individuals. The most abundant species were Neriene peltata, Alopecosa taeniata, Piratula hygrophila and Dismodicus elevatus, all with more than 100 individuals. All sites had between 56 and 62 species and between 445 and 569 individuals.

Introduction

Dominated by taiga (boreal forest) in the centre and south and tundra in the north, Finland (and the neighbouring Scandinavian Peninsula) marks the transition between the temperate and subarctic zones in Europe. With approximately 45000 multicellular species known to occur in the country (Rassi et al. 2010), Finnish biota is of recent origin, as this area was completely covered by ice during the Last Glacial Maximum until as recently as 10000 years ago. Most species have therefore migrated from the south during the last thousands of years, with very few endemic species constituting exceptions. Most groups show relatively low diversity, both at a local scale (alpha diversity) and when comparing sites on their composition (beta diversity). Low diversity, mainly of endemics and a long tradition of taxonomic work for most groups, means that Finnish fauna and flora are well-known, to the point that Finland currently is the only country worldwide where a full set of organisms, from vascular plants and arthropods to birds and mammals, have already been assessed twice for their threat level according to the International Union for the Conservation of Nature (Rassi et al. 2001, Rassi et al. 2010, Juslén et al. 2013, Juslén et al. 2016).

In Finland and despite obvious knowledge gaps on the distribution of species - the Wallacean Shortfall (Lomolino 2004, Cardoso et al. 2011), spiders are particularly well-known. Seppo Koponen recently described the history of Finnish arachnology (Koponen 2010). The first list of Finnish spider species was published by A. von Nordmann in 1863 with 140 species (von Nordmann 1863). By the beginning of the twentieth century, F. W. Mäklin, K. E. Odenwall and T. H. Järvi had increased the list to 255 species (Mäklin 1874, Odenwall and Järvi 1901, Järvi 1906). Later, major taxonomic and faunistic work directed to spiders has been done mainly by P. Palmgren (e.g. Palmgren 1939, Palmgren 1943, Palmgren 1950, Palmgren 1974a, Palmgren 1974b, Palmgren 1975, Palmgren 1976, Palmgren 1977), P. Lehtinen (e.g. Lehtinen 1964, Lehtinen et al. 1979) and S. Koponen (e.g. Koponen 1977, Koponen 1999, Koponen et al. 2007), with more recent additions by T. Pajunen (e.g. Pajunen et al. 2009, Pajunen and Väisänen 2015) and N. Fritzén (e.g. Fritzén 2005, Fritzén 2012, Fritzén et al. 2015). Currently, this list consists of 647 species (Koponen et al. 2016).

The last arachnological paper by Järvi described the spider fauna around the Tvärminne Zoological Station of the University of Helsinki, in southeast Hankoniemi, listing about 150 species (Järvi 1916). Some decades later, Palmgren dedicated extensive and long-lasting research to this same area, reporting 425 species (Palmgren 1972). This region now has one of the best known spider faunas worldwide. The peninsula of Hanko (Hankoniemi) is the southernmost region of Finland, lying just south of 60 degrees north. Its bedrock is a mixture of Precambrian bedrock and a recent end-moraine complex, running as a continuous ridge from the Russian Karelia through the whole of southern Finland and even further into the northern Baltic Sea. Hankoniemi is therefore dominated by moraine or sandy soils, interspersed with strips of calciferous minerals. The area is comparatively rich, with a number of different biotopes and high species richness for the region (it harbours about 15% of the endangered species of Finland). The main habitat type is pine forest (dominated by ), often over consolidated dunes fields. Yet, mixed spruce () and mixed forests are also very common in smaller areas.

During a field course on spider taxonomy and ecology at the University of Helsinki, the authors had the opportunity to sample four plots with the dual objective of both teaching on field methods, spider identification and behaviour and uncovering the spider diversity patterns found in the southern coastal forests of Hankoniemi. As an ultimate goal, this field course intended to contribute to a global project that intends to uncover spider diversity patterns worldwide (see http://biodiversityresearch.org/research/biogeography/). With that purpose, a set of standardised methods and procedures was followed (Cardoso 2009) that allow the comparability of obtained data with numerous other samples being conducted across all continents. By doing so, these data are guaranteed to be reused for multiple future projects currently being implemented.

Sampling methods

Study extent

Four 50 x 50 m plots following a west to east transect were selected for sampling (Table 1). All were in mixed coastal forests dominated by Norway spruce and Scots pine at sea level (0 - 10 m). Plots 1 and 2 were separated by about 100 m, plot 3 was 1.8 km and plot 4 was 5 km from the first (Fig. 1).

Table 1.

Location of sampling plots.

	Latitude	Longitude
Plot 1	59.83226	23.14042
Plot 2	59.83281	23.14137
Plot 3	59.83779	23.17062
Plot 4	59.84147	23.22869

Figure 1.

Location of sampling plots in Hankoniemi, southern Finland. TZS = Tvärminne Zoological Station.

Study dates: Samples were collected in June 2016, with all but pitfall trapping being conducted on the 13th and 14th. Pitfall traps were left in the field between the 13th and 26th of June 2016.

Sampling description

The COBRA - Conservation Oriented Biodiversity Rapid Assessment - protocol at the four plots was followed. This protocol, first proposed for Mediterranean spiders (Cardoso 2009) and very recently adapted for and being applied both on the tropics (Malumbres-Olarte et al. 2016) and islands (Emerson et al. 2017) involves night aerial sampling (4 hours/plot), day/night sweeping (4 hours/plot), day/night beating (4 hours/plot) and pitfall traps (48 traps distributed for 12 samples). In total, it involves about 24 hours of effective work per site (see Cardoso 2009 for details).

Geographic coverage

Description

Hankoniemi, Finland

Coordinates

59.8 and 59.9 Latitude; 23.0 and 23.3 Longitude.

Temporal coverage

Data range: 2016-6-13 – 2016-6-26.

Usage rights

Use license

Open Data Commons Attribution License

Data resources

Data package title

COBRA_Finland_Hankoniemi

Resource link

http://ipt.pensoft.net/resource?r=cobra_hankoniemi_finland

Number of data sets

1

Additional information

Results: A total of 104 species and 1997 adults was collected (Table 2, voucher specimens are deposited at the Finnish Museum of Natural History). Of these, 41 species (39%) were and 13 (12%) . All other families had 6 or less species represented. were also dominant in terms of adult individuals captured, with 1015 (51%), followed by 428 (21%) , 158 (8%) and 145 (7%) . All other families had less than 100 individuals. The most abundant species were , , and , all with more than 100 individuals. All sites had between 56 and 62 species and between 445 and 569 individuals.

Table 2.

Richness and abundance of species per plot (adults only).

Family	Species	Plot 1	Plot 2	Plot 3	Plot 4	Total
Anyphaenidae	Anyphaena accentuata (Walckenaer, 1802)		1		2	3
Araneidae	Araneus marmoreus Clerck, 1757		1			1
Araneidae	Araneus sturmi (Hahn, 1831)		3	5	2	10
Araneidae	Araniella cucurbitina (Clerck, 1757)		1		2	3
Araneidae	Cyclosa conica (Pallas, 1772)	1		1	1	3
Araneidae	Gibbaranea omoeda (Thorell, 1870)	1	1		1	3
Araneidae	Leviellus stroemi (Thorell, 1870)			1		1
Clubionidae	Clubiona comta C. L. Koch, 1839	4	8	5	2	19
Clubionidae	Clubiona lutescens Westring, 1851	1			4	5
Clubionidae	Clubiona subsultans Thorell, 1875		2	2		4
Dictynidae	Dictyna arundinacea (Linnaeus, 1758)		1	4		5
Dictynidae	Dictyna pusilla Thorell, 1856	4	4	7	3	18
Dictynidae	Lathys nielseni (Schenkel, 1932)		1			1
Gnaphosidae	Drassyllus praeficus (L. Koch, 1866)				1	1
Gnaphosidae	Gnaphosa bicolor (Hahn, 1833)	1	4	2		7
Gnaphosidae	Haplodrassus signifer (C. L. Koch, 1839)			1		1
Gnaphosidae	Haplodrassus soerenseni (Strand, 1900)	4	1	3		8
Gnaphosidae	Haplodrassus umbratilis (L. Koch, 1866)	1	1			2
Gnaphosidae	Zelotes clivicola (L. Koch, 1870)		1			1
Hahniidae	Cryphoeca silvicola (C. L. Koch, 1834)	6	12	3	3	24
Linyphiidae	Agyneta cauta (O. Pickard-Cambridge, 1902)	7	12	6	1	26
Linyphiidae	Agyneta ramosa Jackson, 1912	2	5		10	17
Linyphiidae	Agyneta subtilis (O. Pickard-Cambridge, 1863)	1			2	3
Linyphiidae	Anguliphantes angulipalpis (Westring, 1851)		1			1
Linyphiidae	Bathyphantes nigrinus (Westring, 1851)				1	1
Linyphiidae	Bathyphantes parvulus (Westring, 1851)			3	4	7
Linyphiidae	Ceratinella brevis (Wider, 1834)		1			1
Linyphiidae	Dicymbium tibiale (Blackwall, 1836)	1			1	2
Linyphiidae	Diplocentria bidentata (Emerton, 1882)	3				3
Linyphiidae	Diplocephalus picinus (Blackwall, 1841)	1	1			2
Linyphiidae	Diplostyla concolor (Wider, 1834)		3	1	4	8
Linyphiidae	Dismodicus elevatus (C. L. Koch, 1838)	14	36	38	19	107
Linyphiidae	Entelecara congenera (O. Pickard-Cambridge, 1879)			1		1
Linyphiidae	Entelecara erythropus (Westring, 1851)		8	9		17
Linyphiidae	Entelecara flavipes (Blackwall, 1834)		1			1
Linyphiidae	Gongylidium rufipes (Linnaeus, 1758)				19	19
Linyphiidae	Hylyphantes graminicola (Sundevall, 1830)	4		2	1	7
Linyphiidae	Hypomma cornutum (Blackwall, 1833)	3	2		2	7
Linyphiidae	Macrargus rufus (Wider, 1834)	1	1			2
Linyphiidae	Maro minutus O. Pickard-Cambridge, 1906		1			1
Linyphiidae	Maso sundevalli (Westring, 1851)	23	9	32	11	75
Linyphiidae	Micrargus apertus (O. Pickard-Cambridge, 1871)	1				1
Linyphiidae	Minyriolus pusillus (Wider, 1834)	1	2		1	4
Linyphiidae	Moebelia penicillata (Westring, 1851)		2			2
Linyphiidae	Neriene clathrata (Sundevall, 1830)	5	11	3	3	22
Linyphiidae	Neriene peltata (Wider, 1834)	89	169	88	159	505
Linyphiidae	Obscuriphantes obscurus (Blackwall, 1841)	20	12	5	8	45
Linyphiidae	Oedothorax gibbosus (Blackwall, 1841)			1		1
Linyphiidae	Palliduphantes pallidus (O. Pickard-Cambridge, 1871)			1		1
Linyphiidae	Pelecopsis elongata (Wider, 1834)	1	3		1	5
Linyphiidae	Pityohyphantes phrygianus (C. L. Koch, 1836)	3	2	2		7
Linyphiidae	Pocadicnemis pumila (Blackwall, 1841)	1		1	1	3
Linyphiidae	Tenuiphantes alacris (Blackwall, 1853)	3	1	2	15	21
Linyphiidae	Tenuiphantes cristatus (Menge, 1866)			1		1
Linyphiidae	Tenuiphantes tenebricola (Wider, 1834)	21	16	10	23	70
Linyphiidae	Walckenaeria antica (Wider, 1834)			2		2
Linyphiidae	Walckenaeria atrotibialis (O. Pickard-Cambridge, 1878)				2	2
Linyphiidae	Walckenaeria cucullata (C. L. Koch, 1836)	3	1	4	4	12
Linyphiidae	Walckenaeria cuspidata Blackwall, 1833				1	1
Linyphiidae	Walckenaeria dysderoides (Wider, 1834)				1	1
Linyphiidae	Walckenaeria nudipalpis (Westring, 1851)	1				1
Liocranidae	Agroeca brunnea (Blackwall, 1833)		1			1
Lycosidae	Alopecosa taeniata (C. L. Koch, 1835)	87	72	61	61	281
Lycosidae	Pardosa lugubris (Walckenaer, 1802)	2	4	14	3	23
Lycosidae	Piratula hygrophila (Thorell, 1872)	9	3	33	78	123
Lycosidae	Trochosa terricola Thorell, 1856			1		1
Mimetidae	Ero furcata (Villers, 1789)			1		1
Miturgidae	Zora nemoralis (Blackwall, 1861)	3				3
Miturgidae	Zora spinimana (Sundevall, 1833)		3	2	1	6
Philodromidae	Philodromus aureolus (Clerck, 1757)	3			2	5
Philodromidae	Philodromus cespitum (Walckenaer, 1802)	1		1		2
Philodromidae	Philodromus collinus C. L. Koch, 1835	5	10	9	6	30
Philodromidae	Philodromus fuscomarginatus (De Geer, 1778)	1	1		3	5
Philodromidae	Philodromus margaritatus (Clerck, 1757)				1	1
Phrurolithidae	Phrurolithus festivus (C. L. Koch, 1835)	1				1
Pisauridae	Pisaura mirabilis (Clerck, 1757)			1		1
Salticidae	Evarcha falcata (Clerck, 1757)	3	1	12		16
Salticidae	Neon reticulatus (Blackwall, 1853)			2		2
Segestriidae	Segestria senoculata (Linnaeus, 1758)	2	1			3
Tetragnathidae	Metellina mengei (Blackwall, 1869)	30	16	7	29	82
Tetragnathidae	Metellina merianae (Scopoli, 1763)	2				2
Tetragnathidae	Pachygnatha listeri Sundevall, 1830	6	15	12	12	45
Tetragnathidae	Tetragnatha dearmata Thorell, 1873			1		1
Tetragnathidae	Tetragnatha obtusa C. L. Koch, 1837	7	7	5	3	22
Tetragnathidae	Tetragnatha pinicola L. Koch, 1870	1	1	4		6
Theridiidae	Enoplognatha ovata (Clerck, 1757)				4	4
Theridiidae	Episinus angulatus (Blackwall, 1836)		1	1	2	4
Theridiidae	Euryopis flavomaculata (C. L. Koch, 1836)	1	1	3		5
Theridiidae	Neottiura bimaculata (Linnaeus, 1767)			7		7
Theridiidae	Paidiscura pallens (Blackwall, 1834)	15	5	4	15	39
Theridiidae	Parasteatoda lunata (Clerck, 1757)			2	2	4
Theridiidae	Phylloneta sisyphia (Clerck, 1757)			3	1	4
Theridiidae	Platnickina tincta (Walckenaer, 1802)	9	9	11	11	40
Theridiidae	Robertus lividus (Blackwall, 1836)	9	3	3	1	16
Theridiidae	Simitidion simile (C. L. Koch, 1836)			2		2
Theridiidae	Theridion mystaceum L. Koch, 1870		2		1	3
Theridiidae	Theridion pinastri L. Koch, 1872			1	1	2
Theridiidae	Theridion varians Hahn, 1833	3	5	4	3	15
Thomisidae	Diaea dorsata (Fabricius, 1777)	10	5	4	10	29
Thomisidae	Ozyptila atomaria (Panzer, 1801)			1		1
Thomisidae	Ozyptila trux (Blackwall, 1846)		1	8	4	13
Thomisidae	Xysticus audax (Schrank, 1803)	1	3			4
Thomisidae	Xysticus luctuosus (Blackwall, 1836)		4	1		5
Thomisidae	Xysticus obscurus Collett, 1877	2				2
	Species richness	56	62	62	57	104
	Individuals	445	516	467	569	1997

Remarks: The vast majority of species are widespread in Finland and most of Europe. The most notable exception is the uloborid (C. L. Koch, 1834), found for the first time on the Finnish mainland, although only represented here by two juveniles. The species was earlier known in Finland only from Ahvenanmaa, an archipelago on the south-western part of the country (Fritzén 2002) and should be a recent addition due to the effects of global warming that drive a northwards movement of many species until recently only recorded south of the country (Fritzén et al. 2015). Additionally, the linyphiid was found in Finland just a few years ago in the region of Helsinki, about 100 km east from Hankoniemi (Pajunen and Väisänen 2015). Finally, the thomisid , which was considered threatened in the 1980s, is now numerous at Hankoniemi.

Rank	Scientific Name	Common Name
order	Araneae	Spiders