Key to Temnothorax nylanderi species group workers

This key to workers of the Temnothorax nylanderi species group is based on Csösz et al. (2015).

The key is based on nest sample means (which require the investigation of 2 to 3 individuals from each nest). However, because the range of morphometric traits calculated from nest sample means is more or less identical with the 5–95% percentile range of the pool of single individuals, the key is also expected to work on single specimens with high probability (>95%).

See Protocol of Morphometric Character Recording below for definitions of the morphological measurements used within this key.

1

 * Antennomere count: 11. (Body color: yellow. South Europe, Central and East Mediterranean Temnothorax flavicornis
 * Antennomere count: 12

2

 * Median anatomical line of propodeal spine angle value to Weber length in lateral view < 28.5 [20–25°] (Body color: brown. Longitudinal carinae on median region of frons count: present. Longitudinal carinae on medial region of frons shape: forked. Smooth median region on frons count: absent)
 * Median anatomical line of propodeal spine angle value to Weber length in lateral view > 30

3

 * Spine length vs. absolute cephalic size (SPST/CS) > 0.384 [0.391, 0.429]. (Peloponnese peninsula, Greece) Temnothorax laconicus
 * Spine length vs. absolute cephalic size (SPST/CS) < 0.384 [0.324, 0.377]. (South Europe and West Anatolia, Turkey) Temnothorax lichtensteini

4

 * Spine length vs. absolute cephalic size (SPST/CS) < 0.219 [0.159, 0.230]. (Body color: yellow. Smooth median region on frons count: present. Anatolia, Turkey) Temnothorax subtilis
 * Spine length vs. absolute cephalic size (SPST/CS) > 0.219 [0.190, 0.368]

5

 * Postocular distance vs. Maximum height of the petiolar node (PoOC/NOH) > 2.678 [2.526, 3.214]
 * Postocular distance vs. Maximum height of the petiolar node (PoOC/NOH) < 2.678 [2.001, 2.733]

6

 * Spine length vs. absolute cephalic size (SPST/CS) < 0.283 [0.278, 0.331]. (Yellow to brown species.Whole head dorsum homogenously areolate, dull. Europe and North Anatolia, Turkey) Temnothorax parvulus
 * Spine length vs. absolute cephalic size (SPST/CS) > 0.283 [0.200, 0.298]. (Sculpture of head dorsum less homogenous: medially smooth to inconspicuously areolate ground sculpture often superimposed by costulae)

7

 * Frontal carina distance vs. absolute cephalic size (FRS/CS) < 0.334 [0.320, 0.349]. (Head dorsum smooth and shiny. Ground sculpture inconspicuously areolate, smooth and shiny superimposed by feeble costulae only. Anatolia, Turkey) Temnothorax angustifrons
 * Frontal carina distance vs. absolute cephalic size (FRS/CS) < 0.334 [0.335, 0.397]

8

 * Mesosoma longer ML/CS > 1.228 [1.227, 1.272]. Brown species. Head dorsum smooth and shiny. Ground sculpture inconspicuously areolate, smooth and shiny superimposed by feeble costulae only South Anatolia, Turkey Temnothorax similis
 * Mesosoma longer ML/CS < 1.228 [1.155, 1.229]. Yellow to light brown species. Whole head dorsum areolate superimposed be feeble costulae, occasionally narrow median strip inconspicuously areolate, shiny. Greek mainland, Crete and a single record known from North Anatolia, Turkey Temnothorax helenae

Note: Perfect separation of T. helenae from T. ariadnae may be difficult if only a single diagnostic feature is considered.

9

 * Propodeal spines longer: SPST/CL > 0.294 [0.280, 0.338]
 * Propodeal spines shorter: SPST/CL < 0.294 [0.178, 0.307]

10

 * Petiole higher: PEH/CS > 0.402 [0.397, 0.413]. In lateral view frontal profile of petiolar node meeting dorso-caudal plate in an acute angle (72–82°) with a sharp ridge. Endemic to Peloponnese peninsula, Greece Temnothorax angulinodis
 * Petiole lower: PEH/CS < 0.380 [0.366, 0.407]. Petiolar node in lateral view with a concave frontal profile meeting truncate dorsum in an obtuse angle (100–115°) with a narrowly rounded transition, without a conspicuous sharp fronto-dorsal ridge on the petiolar node. Central-East Europe and the Balkans Temnothorax crassispinus

Note: Separation of T. crassispinus from T. crasecundus may be difficult based on a single diagnostic feature.

11

 * Head considerably longer than broad: CL/CWb > 1.179 [1.168, 1.278] with straight sides
 * Head shorter: CL/CWb < 1.179 [0.178, 0.307] sides remarkably convex

12

 * Known from mainland of Europe only
 * Known from Anatolian Turkey and Crete Island

13

 * Petiole longer: PL/CS > 0.422 [0.411, 0.434]. Black species. Main sculpture on head dorsum coarse, longitudinally rugulose and/or carinulate, ground sculpture conspicuously areolate, always dull. Endemic to Dinaran Alps Temnothorax sordidulus
 * Petiole shorter: PL/CS < 0.422 [0.390, 0.422]. Dark brown to black species. Main sculpture on head dorsum coarse, longitudinally rugulose and/or carinulate, ground sculpture conspicuously areolate, always dull. Central and South Europe excluding Dinaran Alps Temnothorax tergestinus

Note: Perfect separation of T. tergestinus from T sordidulus may be difficult if only a single diagnostic feature is considered.

14

 * From dorsal view base of propodeal spines less distant: SPBA/CWb < 0.30 [0.266, 0.300]. Yellow species. Head dorsum smooth and shiny. Ground sculpture inconspicuously areolate, smooth and shiny superimposed by feeble costulae only. Anatolia, Turkey Temnothorax lucidus
 * From dorsal view base of propodeal spines more distant: SPBA/CWb > 0.30 [0.276, 0.341]

15

 * Petiolar node longer: NOL/CS > 0.251 [0.250, 0.288]. Black species. Main sculpture on head dorsum coarse, longitudinally rugulose and/or carinulate, ground sculpture conspicuously areolate, always dull. North Anatolia, Turkey Temnothorax artvinensis
 * Petiolar node shorter: NOL/CS < 0.251 [0.228, 0.248]. Brown to dark brown species. Whole head dorsum uniformly areolate, narrow median strip occasionally inconspicuously areolate, shiny. Endemic to Crete Temnothorax ariadnae

Note: Perfect separation of T. helenae from T. ariadnae may be difficult if only a single diagnostic feature is considered.

16

 * From dorsal view base of propodeal spines less distant: SPBA/CS < 0.283 [0.242, 0.282]
 * From dorsal view base of propodeal spines more distant: SPBA/CS > 0.283 [0.243, 0.321]

17

 * Propodeal spines longer: SPST/CS > 0.262 [0.265, 0.297]. Yellow to brown species. Head dorsum with areolate ground sculpture always superimposed by parallel costulate main sculpture, dull. Central and West Europe: Italy, Austria, Germany and westward Temnothorax nylanderi
 * Propodeal spines shorter: SPST/CS < 0.262 [0.190, 0.259]. Yellow species. Head dorsum smooth and shiny. Ground sculpture inconspicuously areolate, smooth and shiny superimposed by feeble costulae only. Anatolia, Turkey Temnothorax lucidus

18

 * Postocular area shorter: PoOC/CL < 0.375 [0.360, 0.385]. Brown species. Main sculpture of head dorsum heterogeneous: on sides areolate ground sculpture always superimposed by parallel costulate main sculpture, dull, median part of head dorsum shiny. South-Central Anatolia, Turkey Temnothorax schoedli
 * Postocular area longer: PoOC/CL > 0.375 [0.378, 0.405]

19

 * Known from East Europe, the Balkans, Turkey and the Caucasus. Yellow to brown species. Whole head dorsum areolate superimposed by feeble costulae, occasionally narrow median strip inconspicuously areolate, shiny Temnothorax crasecundus
 * Known from Central and West Europe: Italy, Austria, Germany and further west. Yellow to brown species. Head dorsum with areolate ground sculpture always superimposed by parallel costulate main sculpture, dull Temnothorax nylanderi

Protocol of Morphometric Character Recording
Morphometric characters are as defined by Seifert & Csősz (2015). All measurements were made in μm using a pin-holding stage, permitting rotations around X, Y, and Z axes. An Olympus SZX9 stereomicroscope was used at a magnification of x150 for each character, allowing an estimated precision of ± 2 μm. Morphometric data (in μm) are provided in S3 Table. All measurements were made by the first author. Measured characters are defined and abbreviated as follows:
 * CL: maximum cephalic length in median line; the head must be carefully tilted to the position with the true maximum. Excavations of hind vertex and/or clypeus reduce CL (Fig 1A).
 * CS: cephalic size; the arithmetic mean of CL and CWb.
 * CWb: maximum width of head capsule, measured just posterior to the eyes (Fig 1A).
 * EL: maximum diameter of the eye.
 * FRS: distance of the frontal carinae immediately caudal of the posterior intersection points between frontal carinae and the lamellae dorsal to the torulus. If these dorsal lamellae do not laterally surpass the frontal carinae, the deepest point of scape corner pits may be taken as reference line. These pits take up the inner corner of scape base when the scape is fully switched caudad and produce a dark triangular shadow in the lateral frontal lobes immediately posterior to the dorsal lamellae of scape joint capsule (Fig 1B).
 * ML: mesosoma length from caudalmost point of propodeal lobe to transition point between anterior pronotal slope and anterior propodeal shield (preferentially measured in lateral view; if the transition point is not well defined, use dorsal view and take the center of the dark-shaded borderline between pronotal slope and pronotal shield as anterior reference point) (Fig 1D).
 * MW: maximum mesosoma width; this is in workers pronotal width (Fig 1C).
 * NOdL: anterior length of petiole measured in dorsal view. Distance from the centre of anteriormost seta pit on the petiolar node to the level of the constriction of articulation condyle with propodeum. Measuring requires a change of focus from above (seta pit) to below (constriction). Dorsal view is achieved when the dorsalmost point of anterior petiolar peduncle at the level of its strongest constriction and the dorsalmost point of caudal petiolar margin are in the same focal level (Fig 1F).
 * NOH: maximum height of the petiolar node, measured in lateral view from the uppermost point of the petiolar node perpendicular to a reference line set from the petiolar spiracle to the imaginary midpoint of the transition between dorso-caudal slope and dorsal profile of caudal cylinder of the petiole (Fig 1E).
 * NOL: length of the petiolar node, measured in lateral view from petiolar spiracle to dorsocaudal corner of caudal cylinder. Do not erroneously take as reference point the dorso-caudal corner of the helcium, which is sometimes visible (Fig 1E).
 * PEH: maximum petiole height. The chord of ventral petiolar profile at node level is the reference line perpendicular to which the maximum height of petiole is measured (Fig 1D).
 * PEW: maximum width of petiole (Fig 1C).
 * PL: total petiole length measured in dorsal view; distance between the dorsalmost point of caudal petiolar margin and the dorsalmost point of anterior petiolar peduncle at the transversal level of its strongest constriction. Positioning of petiole as in NOdL (Fig 1F).
 * 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 (Fig 1A).
 * PPH: maximum height of the postpetiole in lateral view measured perpendicularly to a line defined by the linear section of the segment border between dorsal and ventral petiolar sclerite (Fig 1D).
 * PPL: maximum length of the postpetiole measured in lateral view perpendicular to the straight section of lateral postpetiolar margin (Fig 1E).
 * PPW: maximum width of postpetiole (Fig 1C).
 * SL: maximum straight line scape length excluding the articular condyle (Fig 1A).
 * SPL: minimum distance between the center of propodeal spiracle and the subspinal excavation measured in lateral view (i.e. the same view that is applied to measure ML). Note: in lateral view propodeal spiracle and the caudal margin of propodeal declivity might not be in the same focal level, hence slight adjust might be necessary while measuring SPL between the two endpoints (Fig 1E).
 * SPBA: the smallest distance of the lateral margins of the spines at their base. This should be measured in dorsofrontal view, since the wider parts of the ventral propodeum do not interfere with the measurement in this position. If the lateral margins of spines diverge continuously from the tip to the base, a smallest distance at base is not defined. In this case, SPBA is measured at the level of the bottom of the interspinal meniscus (Fig 1C).
 * SPST: distance between the center of propodeal stigma and spine tip. The stigma centre refers to the midpoint defined by the outer cuticular ring but not to the centre of real stigma opening that may be positioned eccentrically (Fig 1E).
 * SPTI: the distance of spine tips in dorsal view; if spine tips are rounded or truncated, the centers of spine tips are taken as reference points (Fig 1C).
 * SPWI: maximum distance between outer margins of spines; measured in same position as SPBA (Fig 1C).

The deviation of propodeal spines from longitudinal mesosomal axis (i.e. angle between the spines and the mesosomal axis) is often of high diagnostic value within the Temnothorax nylanderi species-group. Longitudinal mesosomal axis is defined by Seifert et al. (2014) as follows: in lateral view as straight line from the center of propodeal lobe to the border point between anterior pronotal shield and propleuron.