Morphological Measurements/Temnothorax

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The following morphometric characters were used for Temnothorax species by Seifert & Csősz (2015) and Csösz et al. (2015).

  • 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.

Csösz, S., Heinze, J. et al. 2015, Fig. 1.jpg
Fig. 1. Definition of morphological characters of workers of Temnothorax nylanderi species-complex. Head in dorsal view (1) with measurement lines for CL, CWb, PoOC and SL; frontal region of the head dorsum (2) with measurement lines for FRS; dorsal view of mesosoma (3) with measurement lines for MW, PEW, PPW, SPBA, SPTI and SPWI; lateral view of mesosoma (4) with measurement lines for ML, PEH and PPH; lateral view of propodeum, petiole and postpetiole (5) with measurement lines for HOH, NOL, PPL, SPL and SPST; lateral view of propodeum, petiole and postpetiole (6) with measurement lines for NoDL and PPL.

References