Ecology, biology and conservation of Pterostichus rhaeticus Heer, 1837 (Coleoptera: Carabidae) at the edge of its distribution range, in the Western Balkans

Figures & data

Figure 1. Measurements of taxonomic characters: a, male genitalia – right paramere of Pterostichus rhaeticus; b, male genitalia – right paramere of Pterostichus nigrita: L – length of apical portion of paramere, B1 – basal width, B2 – median width, A – apical angle; c, female genitalia – half of the eighth sternite of P. rhaeticus; d, female genitalia – half of the eighth sternite of P. nigrita: L – length, B – breadth, M – length of membranous strip, S – distance from the strip to the basal lobe.

Table I. Overview of Pterostichus rhaeticus and Pterostichus nigrita individuals used in morphometric analysis with respect to their origin from Croatian peatlands.

Study area	Pterostichus rhaeticus		Pterostichus nigrita
	Females	Males	Females	Males
Đon močvar bog	8	6	8	6
Dubravica bog	8	7	–	–
Jarak fen	1	4	10	16

Figure 2. Distribution of Pterostichus rhaeticus in Croatia. Legend: Dubravica bog (circle); Jarak fen (triangle); Đon močvar bog (square).

Table II. Differences in morphological features of Pterostichus rhaeticus and Pterostichus nigrita (means ± standard deviation, SD; minimum and maximum values). Mann-Whitney U test results are shown and asterisks show level of significance; ns – non-significant.

Species	Pterostichus rhaeticus (n = 44)			Pterostichus nigrita (n = 89)			Mann-Whitney test
Morphological features/mm	Mean ± SD	Min	Max	Mean ± SD	Min	Max	U	W	p
Body length, T	11.2 ± 0.49	9.94	12.00	11.64 ± 0.52	10.63	12.86	1075.50	4.07	***
Elytrae length, L	5.52 ± 4.73	4.73	5.93	5.82 ± 0.29	5,25	6.45	888.00	4.07	***
Elytrae width, W1	3.03 ± 2.40	2.40	3.38	3.21 ± 0.18	2.70	3.75	1013.50	4.37	***
Elytrae width, W2	3.48 ± 2.70	2.70	3.90	3.61 ± 0.21	3.00	4.20	1233.00	3,30	***
L/W1	1.82 ± 1.63	1.63	2.16	1.82 ± 0.09	1.67	2.16	1760.50	−0.74	ns
L/W2	1.59 ± 1.43	1.43	1.92	1.62 ± 0.08	1.50	1.93	1588.50	1,58	ns
T/W1	3.69 ± 0.09	3.57	3.86	3.64 ± 0.19	3.30	4.26	1498.00	−2.02	*
T/W2	3.20 ± 0.12	2.88	3.37	3.23 ± 0.17	2.94	3.83	1908.00	0.02	ns

Table III. Differences in morphological features between males and females of Pterostichus rhaeticus and Pterostichus nigrita. Mann-Whitney U test results are shown and asterisks show level of significance; ns – non-significant.

Pterostichus rhaeticus/Pterostichus nigrita	Males (PR n = 17; PN = 39)			Females (PR n = 26; PN n = 50)
Morphological features/mm	U	W	p	U	W	p
Body length, T	192.00	2.48	*	275.50	4.09	***
Elytrae length, L	124.00	3.69	***	196.50	4.96	***
Elytrae width, W1	188.50	2.54	*	294.50	3.89	***
Elytrae width, W2	204.00	2.26	*	379.50	2.96	**
L/W1	322.00	0.16	ns	579.50	−0.77	ns
L/W2	272.00	1.05	ns	539.50	1.20	ns
T/W1	272.50	−1.04	ns	499.00	−1.65	ns
T/W2	308.50	−0.40	ns	603.00	0.51	ns

Table IV. Differences in morphological features between males and females of Pterostichus rhaeticus and Pterostichus nigrita (means ± standard deviation, SD; minimum and maximum values). Mann-Whitney U test results are shown and asterisks show level of significance; ns – non-significant.

Species Pterostichus rhaeticus	Males			Females			Mann-Whitney test
Morphological features/mm	Mean ± SD	Min	Max	Mean ± SD	Min	Max	U	W	p
Body length, T	10.96 ± 0.45	9.94	11.63	11.35 ± 0.45	10.38	12.00	117.50	2.56	**
Elytrae length, L	5.32 ± 0.27	4.73	5.70	5.65 ± 0.19	5.33	5.93	72.00	3.69	***
Elytrae width, W1	2.96 ± 0.22	2.40	3.23	3.08 ± 0.17	2.85	3.38	149.00	1.78	ns
Elytrae width, W2	3.36 ± 0.23	2.70	3.75	3.56 ± 0.18	3.30	3.90	111.00	2.72	**
L/W1	1.81 ± 0.13	1.63	2.16	1.83 ± 0.06	1.71	1.97	160.50	1.49	ns
L/W2	1.59 ± 0.11	1.43	1.92	1.59 ± 0.06	1.48	1.69	196.50	0.60	ns
T/W1	3.72 ± 0.29	3.39	4.61	3.69 ± 0.13	3.41	3.88	200.00	0.51	ns
T/W2	3.28 ± 0.24	3.00	4.10	3.20 ± 0.12	2.88	3.37	184.50	−0.89	ns
Pterostichus nigrita	Males			Females			Mann-Whitney test
Morphological features/mm	Mean ± SD	Min	Max	Mean ± SD	Min	Max	U	W	p
Body length, T	11.33 ± 0.39	10.63	12.31	11.88 ± 0.48	10.75	12.86	355.00	5,12	***
Elytrae length, L	5.62 ± 0.20	5.25	6.08	5.97 ± 0.25	5.25	6.45	268.00	5.84	***
Elytrae width, W1	3.12 ± 0.16	2.70	3.45	3.27 ± 0.17	2.85	3.75	502.00	3.91	***
Elytrae width, W2	3.49 ± 0.19	3.00	3.75	3.69 ± 0.18	3.23	4.20	415.00	4.63	***
L/W1	1.81 ± 0.10	1.67	2.14	1.83 ± 0.09	1.67	2.16	778.00	1.62	ns
L/W2	1.61 ± 0.09	1.50	1.93	1.62 ± 0.07	1.50	1.78	905.50	0.57	ns
T/W1	3.64 ± 0.21	3.30	4.26	3.64 ± 0.18	3.30	4.21	936.00	0.32	ns
T/W2	3.25 ± 0.19	3.00	3.83	3.22 ± 0.14	2.94	3.56	941.00	−0.28	ns

Figure 3. Male genitalia (right paramere) – Pterostichus rhaeticus: a, Dubravica bog; b, Jarak fen; Pterostichus nigrita: c, Jarak fen.

Figure 4. Female structure of eighth abdominal sternite – Pterostichus rhaeticus: a, Đon močvar bog; Pterostichus nigrita: b, Jarak fen.

Figure 5. Male right parameres of Pterostichus rhaeticus and Pterostichus nigrita. Lengths over median width (mm) are plotted against the apical angle (°). Line that separates P. rhaeticus and P. nigrita zones and measurements are based on Luff (1990). P. rhaeticus: Dubravica bog (black circle), Đon močvar bog (black square), Jarak fen (black triangle); P. nigrita: Jarak fen (white triangle), Đon močvar bog (white square).

Figure 6. Female eighth abdominal sternite of Pterostichus rhaeticus and Pterostichus nigrita. Length of membranous strip/distance from membranous strip to start of basal lobe (M/S) plotted against length/breadth (L/B). Measurements are based on Luff (1990). P. rhaeticus: Dubravica bog (black circle), Đon močvar bog (black square), Jarak fen (black triangle); P. nigrita: Jarak fen (white triangle), Đon močvar bog (white square).

Figure 7. Seasonal activity of Pterostichus rhaeticus at three peatlands in Croatia (Dubravica bog, Đon močvar bog, Jarak fen). Data were collected from 2008 to 2010 and monthly catches in pitfall traps were pooled together.

Luff ML. 1990. Pterostichus rhaeticus Heer (Col., Carabidae), a British species previously with P. nigrita (Paykull). Entomologist’s Monthly Magazine 126:245–249.

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