Lepidocyrtus chorus Mateos & Lukić

Mateos, Eduardo & Lukić, Marko, 2019, New European Lepidocyrtus Bourlet, 1839 (Collembola, Entomobryidae) with the first description of feeding-related dancing behaviour in Collembola, Zootaxa 4550 (2), pp. 221-235: 223-233

publication ID

https://doi.org/10.11646/zootaxa.4550.2.4

publication LSID

lsid:zoobank.org:pub:C8D2B580-C156-4075-8FD1-E4A111DAC33F

persistent identifier

http://treatment.plazi.org/id/A2620B55-FFE2-FFF9-FF6C-FF19FD5A8723

treatment provided by

Plazi

scientific name

Lepidocyrtus chorus Mateos & Lukić
status

sp. nov.

Lepidocyrtus chorus Mateos & Lukić  sp. nov.

Figs 1–31View FIGURES 1–4View FIGURES 5–8View FIGURES 9–13View FIGURE 14View FIGURE 15View FIGURES 16–18View FIGURES 19–20View FIGURE 21View FIGURES 22–28View FIGURES 29–31, Table 1

Type material. Holotype: female on slide (slide code: CRBA-77842), Krka National Park , village Oklaj , Town Šibenik, hidropowerplant Miljacka, Croatia, 95 m above sea level, N44°00’04.0” E16°01’05.9”, on stone steps ( Figs 1–2View FIGURES 1–4), hand collecting, 29.iv.2015, leg. M. Lukić.GoogleMaps  Paratypes: 16 females on slides (slide codes LP383-1 to LP383-09, CRBA-77843, and six slides with code CLL4558), and  18 specimens (of unknown sex) in a vial with absolute ethanol (vial code LP383 (3 specimens) and CLL4558 (15 specimens )); same data as holotypeGoogleMaps  . 4 females on slides (code: CLL5100) and  1 specimen (of unknown sex) in a vial with absolute ethanol (vial code CLL5100), 25.ix.2018, leg. N. Sudar; same data as holotypeGoogleMaps  .

The holotype and paratype CRBA-77843 are deposited at the Centre de Recursos de Biodiversitat Animal, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain (http://www.ub.edu/crba/). Paratypes LP383-1 to LP383-09 on slides and three specimens in absolute ethanol (vial code LP383) deposited at the E. Mateos collection, Departament de Biologia Evolutiva , Ecologia i Ciències Ambientals, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain  . 10 paratypes ( CLL4558, six specimens; CLL5100, four specimens) on slides and 16 specimens in absolute ethanol ( CLL4558, 15 specimens; CLL5100, 1 specimen) deposited at the Croatian Biospeleological Society Collection , Zagreb, Croatia  .

Diagnosis. Trunk uniformly white, with one lateral dark-violet spot on each side of abd.IV. Th.II projecting over head. Ant.I-II, legs, ventral tube and posterior region of manubrium with scales. Apical bulb on ant.IV absent. Labial chaetae M 1 M 2 REL 1 L 2 in “p row” well developed and ciliated, R shorter. Dorsal cephalic and body macrochaetae formula as A 0 [A 2a]A 2 A 3 Pa 5 /00/0101+3. Without chaeta s on abd.IV.

Molecular diagnosis. This species includes all populations that cluster with COXII and EF-1α sequences of the individuals LP383-1 to LP383-4 ( Table 1, see also Mateos et al. 2018), with significant support in an adequate molecular delimitation model.

Etymology. The specific name refers to the dance-like behaviour observed in situ. In latin “ chorus  ” means “a dancer”.

Description. Holotype body length 1.6 mm (without head nor furca), paratypes 1.4–1.7 mm. Live specimens of silver color (due to coating of scales, Figs 3–4View FIGURES 1–4), specimens in alcohol white with a dark-violet lateral spot on abd.IV ( Fig. 5View FIGURES 5–8). Th.II projecting over head ( Fig. 5View FIGURES 5–8). Head with a dark-violet apical triangular spot between antennae bases ( Fig. 6View FIGURES 5–8). Ant.II-III-IV slightly violet. Scales densely covering dorsal and ventral surfaces of head, trunk, legs, ventral tube and manubrium, dorsal surface of ant.I-II, and anterior surface of dens ( Figs 7–8View FIGURES 5–8).

Antennal length to head diagonal length ratio (head diagonal measured from cervical edge to apex of mouth part) 1.5–1.7, holotype 1.7. Relation of antennal joints I–IV as 1:1.7–1.9:1.4–1.7:2.7–3.4, in holotype as 1:1.7:1.7:2.7. Ant.I with three dorsolateral small acute chaetae in a triangle (antennal-I-organ sensu Huther, 1986). Ant. III sense organ composed of two bent sensory rods partially behind a cuticular fold ( Fig. 9View FIGURES 9–13). Ant. IV without apical bulb.

Clypeus with twelve ciliated chaetae (3 in row pf, 5 in row f, and 2– 2 in rows L 1 –L 2, respectively). Arrangement of chaetae on labrum 4/554, prelabral chaetae ciliated, first and second row of labral chaetae smooth, apical row branched ( Fig. 10View FIGURES 9–13). Labrum intrusion inverted U-shaped, labral edge with four minute rounded labral papillae with one-pointed end (the lateral papillae) and three-pointed end (the central papillae) ( Fig. 10View FIGURES 9–13). Labial palp with lateral process on papilla E slightly curved, with rounded apical end and reaching apex of papilla ( Fig. 11View FIGURES 9–13). Outer maxillary palp with two smooth chaetae and three smooth sublobal chaetae ( Fig. 12View FIGURES 9–13).

Labium chaetotaxy formed by 5 smooth chaetae (a1–a5) in anterior row; basal row with ciliated chaetae M 1 M 2 REL 1 L 2 ( Fig. 13View FIGURES 9–13) with R smaller than other chaetae (ratio of R/M ~0.4). Postlabial chaetotaxy ( Fig. 13View FIGURES 9–13) with 4+4 ciliated chaetae along ventral cephalic groove.

Dorsal cephalic macrochaetae formula A 0 A 2 A 3 Pa 5 ( Fig. 14View FIGURE 14), but also with pair of smaller supplementary macrochaetae A 2a between A 0 and A 2; maximum number of macrochaetae An on head 13+13.

Eye patches dark blue. Diameters of eyes A–F about the same. Eyes G and H slightly smaller (A:G; A:H = 1.5). Interocular chaetotaxy ( Fig. 14View FIGURE 14) with s, t, q chaetae and 2–3 intraocular scales.

In Fig. 15View FIGURE 15 are represented all the elements composing dorsal body chaetotaxy. Dorsal body macrochaetae formula 00/0101+3 (m3 on abd.II, C1+B4, B5, B6 on abd.IV). Dorsal chaetotaxy of th.II–III and abd.I as in Figs 16–18View FIGURES 16–18. Th.II with 2 lateral S-chaetae (al and ms) and without macrochaetae in dorsal position. Th.III with a lateral sensillum (al) between two ciliated chaetae. Abd.I with a lateral S-microchaeta (ms) external to a6. Chaetotaxy of abd.II–III as in Figs 19–20View FIGURES 19–20. Abd.II chaetotaxy between the two dorso-medial trichobothria with mesochaetae a2, a3, a2p, m3e, p4, sens as and macrochaeta m3; macrochaeta m5 with socket of similar size of macrochaeta m3. Abd.III with S-chaetae as and ms; chaeta d3 present. Chaetae associated with trichobotria on abd.II–III fan-shaped. Chaetotaxy of abd.IV as in Fig. 21View FIGURE 21; macrochaetae B4, B5, B6, C1, D3, E2, E3, E4, F1, F2, F3 and T6 broader with broad socket (bcM in Fig. 15-aView FIGURE 15), while D2, De3, D3p, E1, E4p, F3p, Fe4, Fe5, r3 and T7 thinner with smaller socket (tcM in Fig. 15-bView FIGURE 15); macrochaeta F2 above macrochaeta E3; the ratio of distances between macrochaetae C1–B4 / B4–B6 1.1–1.3; accessory chaeta s associated with trichobotrium T2 absent; all chaetae associated with trichobotria on abd.IV (D1, a, m, pe, pi) fan-shaped; sens chaetotaxy composed by 2 anterior dorsomedial elongate S-chaetae (S in Fig. 21View FIGURE 21 and Fig. 15-eView FIGURE 15), as and ps. Dorsal chaetotaxy of abd.V as in Fig. 22View FIGURES 22–28; with S-chaetae as, acc.p4 and acc.p5.

Trochanteral organ with 12–14 smooth spiny chaetae forming a V shape pattern ( Fig. 23View FIGURES 22–28). Ungues ( Fig. 24View FIGURES 22–28) with paired basal teeth at 54% from inner edge, one sub-equal median tooth at 70%, and a tiny apical tooth at 86% from inner edge, respectively; three external teeth, 2 paired laterally and 1 unpaired basally, also present; unguiculi lanceolate, with denticles along outer edge, some specimens with unguiculi II-III smooth or with tiny denticles; tibiotarsal tenent hair spatulate, smooth and as long as claw; ratio of supraempodial chaeta (smooth chaeta on tibiotarsus III opposite to tenent hair) / unguiculus is around 0.7.

Ventral tube with a maximum of 5+5 ciliated chaetae on anterior side ( Fig. 25View FIGURES 22–28) and 15 weakly ciliated chaetae on posterior side; lateral flap with a maximum of 18 laterodistal chaetae (6 ciliated and 12 smooth, Fig. 26View FIGURES 22–28).

Manubrium with 2+2 ciliated apical chaetae on anterior side; manubrial plate with 3–4 inner chaetae and 6–9 chaetae outer to the 2 pseudopores ( Fig. 27View FIGURES 22–28). Dental tubercle absent. Mucro without spinelet on basal spine ( Fig. 28View FIGURES 22–28). Ratio manubrium/dens/mucro as 17.5:21.5:1.

Ecology and distribution. The specimens of L. chorus  sp. nov. were found on old stone steps in the backyard of the hydropower plant ( Figs 1–2View FIGURES 1–4). Limestone steps are situated at 95 m above sea level, at the bottom of a 100 m deep canyon of the river Krka, partially covered by leaf litter and fine gravel, and overgrown by biofilm. The region is characterized by warm Mediterranean climate, type Cfsa according to Köppen climate classification ( Milković & Trninić 2007), with mean air temperature when species was observed being 12.1°C for April 2015 and 13.5°C for October 2016 (data for the nearby meteorological station Knin; time period 1949–2017) (data available at http://www.meteo.hr).

All specimens mounted on slides (17 specimens) collected on 29.iv.2015 had the gut completely and exclusively full of tricolpate pollen grains possibly of Brassica  L. species. This pollen was clearly visible inside the gut due to the clearing procedure with Nesbitt fluid applied to the specimens. The gut of the four mounted specimens collected on 25.ix.2018 contained plant material, fungal hyphae, conidia, pollen grains and brown amorphous material. Pollen grains of several plants were recorded in three out of four specimens but were not the dominant type of food in the gut.

This species is known only from its type locality.

Dancing behaviour. Video is available on YouTube (https://youtu.be/8pspWYQroEI) and deposited on Figshare (https://doi.org/10.6084/m9.figshare.7380836. v1). Peculiar dance-like behaviour of the L. chorus  sp. nov. was observed during the sampling on 29.iv.2015 and 25.ix.2018. Two types of dance could be identified: ‘grazing dance’ and ‘walking dance’. During grazing dance individuals retain their head position while feeding and at the same time make rapid circular clockwise and counter clockwise movement of the abdomen ( Figs. 29–30View FIGURES 29–31, for example see video at 00:37). When finished with grazing individuals continue with walking dance where they progress with the movement in a certain direction and at the same time continue with the rapid circular movement of the abdomen ( Fig. 31View FIGURES 29–31, for example see video at 00:30 and 01:13). Individuals were usually few centimetres apart from each other and there was no obvious interaction between them. When coming in closer contact, they did not change their behaviour and continue with the dance, usually moving away from each other. On 07.x.2016, additional footage of this dance-like behaviour was captured with macro lenses that revealed more details. The behaviour of the specimens on this occasion was similar, although the circular movement of the abdomen was less conspicuous (for example see video at 02:22). Individuals were also observed grazing without circular movement of the abdomen. On this occasion two specimens were photographed in close interaction while grazing ( Figs 3–4View FIGURES 1–4).

Discussion. Morphological characters clearly assign Lepidocyrtus chorus  sp. nov. to the Lepidocyrtus lignorum  -group (sensu Mateos 2011). Also, genetic sequences done by Mateos et al. (2018) clearly place the new species in this European species group. Currently L. lignorum  -group is composed by 12 species (13 with the inclusion of L. chorus  sp. nov.), namely L. barbulus Mateos, 2011  , L. instratus Handschin, 1924  , L. intermedius Mateos, Escuer & Álvarez-Presas, 2018  (in Mateos et al. 2018), L. juliae Mateos, 2011  , L. lignorum ( Fabricius, 1793)  , L. peisonis Traser & Christian, 1992  , L. ruber Schött, 1902  , L. tellecheae Arbea & Jordana, 1990  , L. traseri Winkler, 2016  , L. uzeli Rusek, 1985  , L. vexillosus Loksa & Bogojević, 1967  and L. violaceus Lubbock, 1873  . All of them have trunk macrochaetotaxy formula 00/0101+3. The dorsal head macrochaetotaxy formula A 0 A 2 A 3 Pa 5 is also shared by all species of the group (and also by L. chorus  sp. nov.) except L. intermedius  (A 0 A 2 Pa 5), L. ruber  (A 0 A 2 A 3) and L. vexillosus  (A 0 A 2 Pa 5)

Lepidocyrtus chorus  sp. nov. shares the body colour pattern with L. vexillosus  (one dark spot on each side of abd.IV), but can be clearly differentiated from it because L. vexillosus  lack dorsal cephalic macrochaeta A3 and, in the foot complex, has the unguis paired basal teeth in more apical position (76% from the inner edge), very reduced unguis apical tooth, and unguiculus without denticles (see Loksa & Bogojević, 1967). By the characteristic body colour pattern L. chorus  sp. nov. clearly differs from all the other species of the L. lignorum  -group; further differences include the morphology of abd.IV chaetae r3 (thin ciliated macrochaeta in L. chorus  sp. nov. and smooth mesochaeta in all the other species) and T6 (broad ciliated macrochaeta in L. chorus  sp. nov. and thin ciliated macrochaeta in all the other species). Other particular differences of L. chorus  sp. nov. with each above mentioned species include: two M chaetae in labial chaetotaxy (more than two in L. barbulus  ), mesothorax slightly projecting over the head (strongly projecting in L. instratus  ), without ocular chaeta q and lateral pseudopores on abd.IV (present in L. juliae  , unpublished data), unguiculus acuminate (truncate in L. peisonis  , L. ruber  and L. uzeli  ), apex of third row of labral chaetae branched (simple in L. tellecheae  ), abd.IV chaeta B6 broad ciliated macrochaeta (thin ciliated macrochaeta in L. traseri  ), ratio of distances between macrochaetae C1–B4 / B4–B6 1.1– 1.3 (0.53–0.75 in L. lignorum  and 0.61–0.72 in L. violaceus  ). Also L. chorus  sp. nov. clearly differs from L. barbulus  , L. juliae  , L. intermedius  , L. lignorum  , L. tellecheae  and L. violaceus  in the phylogenetic analyses of genes CoxII and EF-1α done by Mateos et al. (2018).

Analyses of gut content revealed definite preference of L. chorus  sp. nov. for feeding on pollen of just one plant species (possibly of a Brassica  species) at the time of the sampling on 29.iv.2015, while on 25.ix.2018 the gut was filled with plant material, fungal hyphae, conidia, brown amorphous material but also with pollen of several plant species. Unfortunately, filmed specimens on 07.x.2016 are not available for the study of gut content. In the detailed overview of Collembola  as pollen feeders, Kevan & Kevan (1970) gave several dozen of Collembola  species, among them at least three Lepidocyrtus  species, that have been recorded ingesting pollen either directly by visiting flowers or probably feeding on wind-borne pollen. Pollen wall characteristics (porosity, thickness, and composition) are responsible for differences in digestibility among pollen types by animals ( Roulston & Cane 2000). Some Collembola  species, like Onychiurus pseudofimetarius Folsom  , can digest the pollen wall ( Scott & Stojanovich 1963), but not all species possess this digestive ability. To crack open the pollen wall mechanically is another method used to extract pollen content ( Roulston & Cane 2000), and the mandibular molar plate of Lepidocyrtus  could be useful for this method of digesting pollen grains. Some pollen grains in the gut of L. chorus  sp. nov. had the wall broken meaning that their content was digested. With the data available we can hypothesize that L. chorus  sp. nov. feeds exclusively on pollen grains during bloom of certain plants and favors this type of food but also feed oportunistically during other seasons.

Feeding preference and occasional grazing during dancing of L. chorus  sp. nov. suggest that such behaviour is probably related to feeding and searching for the wind-borne pollen deposited on the stone surface and possibly other type of food. In support comes the fact that during dancing no courtship or spermatophore transfer has been observed and that subadults and juvenile specimens have also been observed dancing, leading to conclusions that it is not related to mating. Somewhat similar dance related to search for food is described for the blowfly Phormia regina (Meigen)  , where specimens perform a series of loops and spirals rather than straight line movement when they come in contact with the sugar (Dethier l957, Nelson 1977).

To our knowledge, this is the first record of peculiar dancing behaviour related to feeding among Collembola  . Laboratory experiments on L. chorus  sp. nov. is needed to confirm that the dance is triggered by the presence of certain type of food and exclusively related to feeding.

Kingdom

Animalia

Phylum

Arthropoda

Class

Collembola

Order

Collembola

Family

Entomobryidae

Genus

Lepidocyrtus

Loc

Lepidocyrtus chorus Mateos & Lukić

Mateos, Eduardo & Lukić, Marko 2019
2019
Loc

Lepidocyrtus chorus

Mateos & Lukić 2019
2019
Loc

L. chorus

Mateos & Lukić 2019
2019
Loc

L. chorus

Mateos & Lukić 2019
2019
Loc

L. chorus

Mateos & Lukić 2019
2019
Loc

L. chorus

Mateos & Lukić 2019
2019
Loc

L. chorus

Mateos & Lukić 2019
2019
Loc

L. chorus

Mateos & Lukić 2019
2019
Loc

L. chorus

Mateos & Lukić 2019
2019
Loc

L. chorus

Mateos & Lukić 2019
2019
Loc

L. intermedius

Mateos, Escuer & Alvarez-Presas 2018
2018
Loc

L. traseri

Winkler 2016
2016
Loc

L. barbulus

Mateos 2011
2011
Loc

L. juliae

Mateos 2011
2011
Loc

L. barbulus

Mateos 2011
2011
Loc

L. juliae

Mateos 2011
2011
Loc

L. peisonis

Traser & Christian 1992
1992
Loc

L. tellecheae

Arbea & Jordana 1990
1990
Loc

L. tellecheae

Arbea & Jordana 1990
1990
Loc

L. uzeli

Rusek 1985
1985
Loc

L. vexillosus

Loksa & Bogojevic 1967
1967
Loc

L. vexillosus

Loksa & Bogojevic 1967
1967
Loc

L. instratus

Handschin 1924
1924
Loc

Onychiurus pseudofimetarius

Folsom 1917
1917
Loc

L. ruber

Schott 1902
1902
Loc

L. violaceus

Lubbock 1873
1873
Loc

L. violaceus

Lubbock 1873
1873
Loc

Lepidocyrtus

Bourlet 1839
1839
Loc

Lepidocyrtus

Bourlet 1839
1839