Laccophilus paraguensis Régimbart

Michat, Mariano C., 2008, Description of the larvae of three species of Laccophilus Leach and comments on the phylogenetic relationships of the Laccophilinae (Coleoptera: Dytiscidae), Zootaxa 1922, pp. 47-61 : 54-57

Laccophilus paraguensis Régimbart ( Figs. 6 , 12, 15 , 27, 31 , Tables 1–2 )

Distribution. Laccophilus paraguensis inhabits Brazil, Paraguay, Bolivia, and the Argentinean provinces of Buenos Aires, Chaco and Entre Ríos ( Trémouilles 1998; Benetti et al. 2003).

Source of material. Nine specimens of instar I, four of instar II and three of instar III were used for the descriptions. Larvae were collected in association with adults at the following locality: Argentina, Buenos Aires City, 22-X-2001 to 2-IV-2002, temporary rain pools 20–30 m long, with clear water, soil bottom and abundant vegetation (mainly grasses), and oval-shaped permanent pond about 30 m in diameter, with marginal aquatic vegetation.

Diagnosis. Color of cephalic capsule as in Figs. 6 (instar I) and 27 (instar III). Head width = 0.40–0.44 mm (instar I), 0.60–0.69 mm (instar II) and 0.95–0.99 mm (instar III) ( Table 1 ). Cephalic capsule subtriangular, without neck constriction (instar I). Distal third of ventrointernal margin of MN with denticles (instar I) ( Fig. 12 ). Legs more densely covered with minute slender spinulae (instar I). Seta AN3 located dorsally (instar I). Setae MX 5 and MX 6 somewhat curved posteriorly (instar I) ( Fig. 15 ). Seta FE5 short on mesoFE, elongate on metaFE (instar I). Seta AB11 short (instar I). Cephalic capsule with 3–5 spine-like secondary setae on each lateral margin of PA and 1–6 spine-like secondary setae on each side of ventral surface of PA (instars II-III) ( Fig. 27 ). Meso- and metatergite with two spine-like secondary setae on each side and 3-6 spine-like secondary setae on central portion (instar II). U with several hair-like secondary setae (instar II). FR with reticulation (instar III). A3 and A1 subequal in length (instar III) ( Table 1 ). CO with a greater number of secondary setae (instar III) ( Table 2 ). Measurements and ratios that characterize body shape are shown in Table 1 . Secondary leg setation is detailed in Table 2 .

Description of color. Instar I. Dorsal surface of cephalic capsule light brown except for anterolateral angles testaceous, one large, V-shaped, testaceous macula centrally, one large testaceous macula medially posterior to spatulate setae, and one small testaceous macula laterally posterior to each ocular area ( Fig. 6 ); ventral surface of cephalic capsule testaceous to light brown; head appendages testaceous to light brown, MN slightly darker; thoracic and abdominal sclerites light brown; membranous parts white; legs testaceous to light brown; U light brown. Instar II. As instar I except: testaceous maculae on anterolateral angles of cephalic capsule and posterior to spatulate setae weakly marked. Instar III. As instar II except: basal area near occipital foramen testaceous; light brown areas on dorsal surface of cephalic capsule with brown maculae; thoracic tergites light brown with brown maculae, lateral portions of protergite testaceous.

L. obliquatus L. paraguensis

Segment Position Instar II Instar III Instar II Instar III

Figures

FIGURES 5 – 7. Laccophilus, first-instar larva, color pattern of cephalic capsule, dorsal aspect: 5, L. obliquatus; 6, L. paraguensis; 7, L. testudo. Scale bars = 0.10 mm.

FIGURES 8 – 18. Laccophilus, first-instar larva. 8 – 9, L. obliquatus, antenna: 8, dorsal aspect; 9, ventral aspect. 10, L. testudo, antenna, ventral aspect. 11, L. obliquatus, mandible, dorsal aspect. 12, L. paraguensis, mandible, ventral aspect. 13 – 14, L. obliquatus, maxilla: 13, dorsal aspect; 14, ventral aspect. 15, L. paraguensis, maxilla, ventral aspect. 16, L. testudo, maxilla, ventral aspect. 17 – 18, L. obliquatus, labio: 8, dorsal aspect; 9, ventral aspect. Scale bars = 0.04 mm.

FIGURES 26 – 31. Laccophilus, third-instar larva. 26, L. obliquatus, head, dorsal aspect. 27, L. paraguensis, head, dorsal aspect. 28 – 29, L. obliquatus, prothoracic leg: 28, anterior aspect; 29, posterior aspect. 30, L. obliquatus, abdominal segment VIII and urogomphi, dorsal aspect. 31, L. paraguensis, abdominal segment VIII and urogomphi, dorsal aspect. Scale bars = 0.20 mm.

Tables

TABLE 1. Measurements and ratios for the larvae of three species of Laccophilus. Three specimens of each instar were measured for each species.

		L. obliquatus		L. paraguensis	L. testudo
Measure	Instar I	Instar II Instar III	Instar I	Instar II Instar III	Instar I
TL (mm)	1.20–2.30	2.00–3.60 3.40–5.00	1.80–2.00	2.40–3.10 4.40–6.50	2.10–3.00
MW (mm)	0.25–0.30	0.50–0.60 0.80–0.90	0.25–0.35	0.40–0.70 0.90–1.10	0.35–0.50
HL (mm)	0.43–0.45	0.66–0.68 0.95–0.99	0.50–0.52	0.77–0.82 1.10–1.16	0.60–0.62
HW (mm)	0.33–0.36	0.50–0.52 0.77–0.79	0.40–0.44	0.60–0.69 0.95–0.99	0.50–0.52
FRL (mm)	0.30–0.31	0.40–0.42 0.50–0.51	0.36–0.39	0.48–0.54 0.65–0.69	0.46
OCW (mm)	0.13–0.14	0.21–0.24 0.39–0.45	0.18–0.21	0.28–0.29 0.51–0.56	0.22–0.24
HL/HW	1.25–1.31	1.29–1.33 1.21–1.30	1.19–1.28	1.17–1.27 1.15–1.18	0.15–0.26
HW/OCW	2.31–2.77	2.21–2.48 1.77–2.03	2.12–2.22	2.00–2.18 1.77–1.85	2.21–2.30
COL/HL	0.30–0.31	0.38–0.40 0.47–0.49	0.26–0.30	0.31–0.37 0.40–0.41	0.25–0.27
FRL/HL	0.69–0.70	0.60–0.62 0.51–0.53	0.71–0.74	0.62–0.69 0.59–0.60	0.73–0.75
A/HW	0.88–0.96	0.73–0.83 0.67–0.71	0.91–0.97	0.81–0.86 0.72–0.75	0.85–0.88
A3/A1	1.50–1.56	1.30–1.39 1.21–1.26	1.25–1.50	1.20–1.32 0.98–1.04	1.39–1.55
A3/A2	1.53–1.79	1.45–1.52 1.43–1.56	1.32–1.43	1.25–1.33 1.12–1.21	1.33–1.55
A4/A3	0.30–0.40	0.27–0.31 0.22–0.25	0.34–0.44	0.26–0.28 0.21–0.25	0.33–0.39
A3’/A4	1.00	0.89–0.90 0.89–0.90	0.91–1.00	0.91–1.00 0.83–0.91	0.67–0.82
MNL/MNW	2.93–3.14	2.86–3.05 3.07–3.14	2.70–2.84	2.77–2.96 2.87–3.06	2.74–2.95
MNL/HL	0.49–0.51	0.47 0.43–0.46	0.49–0.52	0.45–0.51 0.47–0.48	0.49–0.52
A/MP	1.07–1.14	1.03–1.19 1.07–1.17	1.20–1.25	1.21–1.27 1.21–1.23	1.14–1.19
GA/MP1	0.43–0.50	0.36–0.41 0.30–0.35	0.44–0.47	0.38–0.45 0.37–0.43	0.42–0.50
PPF/MP1	0.21	0.18 0.18–0.21	0.24–0.25	0.23–0.27 0.21–0.24	0.21–0.33
MP2/MP1	1.14–1.21	1.05–1.09 0.94–0.97	1.13–1.29	1.15–1.27 1.05–1.11	1.32–1.44
MP2/MP3	0.59–0.67	0.79–0.83 0.97–1.03	0.67–0.75	0.79–0.93 0.95–1.08	0.74–0.81
MP/LP	2.70–3.00	2.64–2.92 2.77–2.88	2.65–2.88	2.67–2.88 2.53–2.64	2.53–2.89
LP2/LP1	2.33–3.00	1.70–1.89 1.27–1.50	2.00–2.29	1.43–1.67 1.24–1.30	2.00–2.38
L3 (mm)	1.33–1.37	1.98–2.03 2.87–2.99	1.49–1.66	2.25–2.51 3.41–3.60	1.82–1.88
L3/L1	1.26–1.30	1.33–1.36 1.35–1.36	1.28–1.34	1.34–1.37 1.39–1.42	1.30–1.33
L3/L2	1.11–1.15	1.15–1.18 1.17–1.20	1.14–1.16	1.16–1.18 1.19–1.20	1.13–1.16
L3/HW	3.84–4.14	3.86–4.03 3.75–3.80	3.75–3.85	3.58–3.76 3.52–3.66	3.53–3.69
L3 (CO/FE)	1.00–1.09	1.02–1.08 1.07–1.10	0.96–1.00	0.98–1.02 0.99–1.04	0.95–1.04
L3 (TI/FE)	0.79–0.86	0.80–0.84 0.78–0.81	0.79–0.82	0.77–0.78 0.76–0.80	0.81–0.83
L3 (TA/FE)	1.11–1.18	1.04–1.07 0.96–0.99	1.04–1.08	0.95–1.02 0.88–0.93	1.02–1.05
L3 (CL/TA)	0.40–0.43	0.34–0.35 0.25–0.27	0.40–0.43	0.33–0.37 0.27–0.29	0.35–0.38
LAS (mm)	0.16	0.33–0.34 0.58–0.64	0.18–0.20	0.38–0.42 0.70–0.75	0.22
LAS/HW	0.46–0.48	0.64–0.69 0.74–0.83	0.45–0.47	0.58–0.62 0.73–0.76	0.42–0.44
U (mm)	0.79–0.83	1.49–1.66 1.69–1.80	0.93–0.95	1.56–1.79 1.49–1.69	0.98–1.09
U/LAS	4.97–5.22	4.51–4.86 2.65–2.98	4.73–5.25	4.14–4.53 2.11–2.24	4.50–4.91
U/HW	2.29–2.49	2.90–3.18 2.20–2.30	2.12–2.36	2.54–2.63 1.57–1.71	1.92–2.08
U1/U2	6.59–8.06	3.18–4.45 50.29–67.80	5.30–6.56	3.47–4.15 32.56–41.63	3.60–4.12