Seifert 2020 Lasius characters

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The following information is from Seifert, B. 2020. A taxonomic revision of the Palaearctic members of the subgenus Lasius s.str. (Hymenoptera, Formicidae). Soil Organisms 92(1): 15-86 (doi:10.25674/so92iss1pp15).

Eighteen morphometric characters (seven shape, eight seta and two pubescence characters as well as absolute size (indicated by CS) are defined below – figures assisting the definition of these characters are given in Seifert (2018). All bilateral characters were recorded as arithmetic mean of both sides. MaDe and PLF are frequently not recordable or difficult to evaluate – the former because of complete mandibular adduction and the latter because of conglutination of pubescence hairs. As a consequence, MaDe and PLF are usually excluded from multiple NUMOBAT analyses and only the 16 remaining characters are called ”standard characters“.

  • CL – maximum cephalic length in median line; the head must be carefully tilted to the position with the true maximum. Excavations of posterior head and/or clypeus reduce CL.
  • CS – arithmetic mean of CL and CW as less variable indicator of body size.
  • CW – maximum cephalic width; this is either across, behind, or before the eyes.
  • dClAn – torulo-clypeal distance: the shortest distance from posterior clypeal suture (PCS) to inner margin of antennal torulus (socket). The right spatial adjustment is given when upper and lower portions of this inner margin superimpose. If no surface structure indicates the position of PCS, the center of the dark line is taken as the anterior measuring point.
  • EYE – eye-size: the arithmetic mean of the large (EL) and small diameter (EW) of the elliptic compound eye under consideration of all structurally visible ommatidia - i.e., including also unpigmented ones.
  • GuHL – maximum length of setae on underside of head (”gula“).
  • MaDe – number of mandibular dents; suggested denticles may score in the count as 0.5.
  • MP6 – length of the sixth (terminal) segment of maxillary palps.
  • nGen – with head in full face view, number of setae on head sides frontal of anterior eye margin (”gena“). The bilateral sum is halved.
  • nGu – number of setae on underside of head (”gula“) as seen in full profile. The bilateral sum is halved.
  • nHT – setae number on extensor profile of hind tibia under exclusion of the very apical setae. The bilateral sum is halved.
  • nOcc – setae number projecting from hind margin of vertex frontad to caudal end of eye. Counting is done with head in full face view and by rotating the head within visual plane to avoid a parallax error in estimating the 20 μm projecting distance. Keep care to avoid the parallax error when determining the anterior end of the counting line that is at level of posterior eye margin. The bilateral sum is halved.
  • nSc – setae number on dorsal plane of scape under exclusion of the most apical setae, counted with view on the small scape diameter. The bilateral sum is halved.
  • nSt – setae number on lateral and caudolateral surface of metapleuron. The upper margin of the counting area is an imagined line parallel to the lower straight margin of metapleuron and crossing the lower margin of the cuticular ring of propodeal spiracle. Protective setae fringing the orifice of the metapleural gland are excluded. The bilateral sum is halved.
  • PLF – mean length of pubescence hairs on head between the frontal carinae. At least seven measurements in each individual are averaged. In case of extremely dense pubescence making length measurement impossible, a partial ablation of pubescence may be performed.
  • PnHL – length of the longest hair on pronotum.
  • PoOc – postocular distance. Use a cross-scaled ocular micrometer and adjust the head to the measuring position of CL. Caudal measuring point: median occipital margin; frontal measuring point: median head at the level of the posterior eye margin. Note that many heads are asymmetric and average the left and right postocular distance.
  • SL – maximum straight line scape length excluding the articular condyle.
  • sqPDCL – square root of pubescence distance PDCL on clypeus. The number of pubescence hairs crossing or just touching a census line from caudomedian clypeus to lateral clypeal depression is counted. Hairs crossing / touching the census line are counted as 1 / 0.5. Erroneous zero counts in surface areas with torn-off pubescence can be avoided when the basal points of the missing hairs can be visualized by adequate illumination and high-resolution optics and when average pubescence hair length is considered. Square root data transformation is applied to normalize positively skewed distributions. 3.3 Removal of allometric variance

There is a strong intraspecific variance of body size in Lasius ants which is determined by age and social structure of the colonies and by nutrition. In order to create comparative tables in which shape variables differ between the species independent of body size, a removal of allometric variance (RAV) was performed following the basic procedure described by Seifert (2008). Evaluation of scatter plots suggested a use of linear monophasic allometry functions. RAV was calculated assuming all individuals to have a cephalic size of CS=900 μm. RAV functions were calculated as the arithmetic mean of the species-specific functions of 47 Palaearctic Lasius s.str. species with sufficient sample size. The RAV functions of six shape, eight seta, two pubescence and one dentition character are given in the following.

  • CL/CW900 = CL/CW / (-0.2290 CS +1.2804)*1.0743
  • SL/CS900 = SL/CS / (-0.2095*CS +1.1771)*0.9886
  • nSC900 = nSc / (+13.04*CS -2.50)*9.23
  • nGen900 = nGen / (+7.11*CS -1.89)*4.50
  • nOcc900 = nOcc / (+9.00*CS +3.27)*11.37
  • nGu900 = nGu / (+8.38*CS-1.54)*6.00
  • nHT900 = nHT / (+19.02*CS -6.73)*10.39
  • nSt900 = nSt / (+7.14*CS -2.73)*3.70
  • sqPDCL900 = sqPDCL / (-0.992*CS +5.619)*4.726
  • PoOc/CL900 = PoOc/CL / (-0.0194*CS +0.2517)*0.2342
  • EYE/CS900 = EYE/CS / (-0.0704*CS +0.3017)*0.2383
  • dClAn/CS900= 100*dClAn/CS/(+0.287*CS +4.249)*4.507 [given in %]
  • GuHL/CS900 = GuHL/CS/(-0.0108*CS+0.1179)*0.1082
  • PnHL/CS900 = PnHL/CS/(+0.0001*CS+0.1425)*0.1425
  • MP6/CS900 = MP6/CS / (-0.0806*CS +0.2512)*0.1886
  • PLF900 = PLF / (+21.99*CS +9.49)*29.19
  • MaDe900 = MaDe / (+0.55*CS +7.62)*8.11