Photinus extensus Gorham, 1881
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publication ID |
https://dx.doi.org/10.3897/zookeys.1104.80624 |
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publication LSID |
lsid:zoobank.org:pub:68CE42A1-3B99-441B-B15D-8E163C06A40B |
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persistent identifier |
https://treatment.plazi.org/id/73B0A7FE-746C-5424-B3CB-E35C150B1C7D |
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treatment provided by |
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scientific name |
Photinus extensus Gorham, 1881 |
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Photinus extensus Gorham, 1881
Figs 3A-E View Figure 3 , 4A-E [Adults] View Figure 4
Redescription. Adult male
(Fig. 3A, B View Figure 3 ) (n = 70). Length of body 16.1-20.3 mm; width 3.7-4.2 mm. Body brownish, except the pronotal disk with a central black spot and two red spots at the sides; protrochanters, coxae, seventh and eighth ventrites yellowish; light organ in sternites 5-6 and 7th sternite with diminished light spots.
Head. Interocular space flat, almost parallel, shagreen-like integument, brilliant and pilose; frons vertical, interantennal distance (0.17-0.22 mm; 0.2 ± 0.01 mm) slightly wider than the antennal fossae (0.23-0.32 mm; 0.28 ± 0.04 mm); eyes finely faceted, semispherical, prominent, longer (1.1-1.18 mm; 1.17 ± 0.03 mm) than wide (0.62-0.98 mm; 0.9 ± 0.08 mm); antennae filiform, long (5.7-7.11 mm; 7.0 ± 0.11 mm), one-and-a half times longer than pronotum, extending beyond the posterior coxae, scape claviform reaching a length of (0.69-0.98 mm; 0.79 ± 0.10 mm), as long as the next two antennomeres together, the second short (0.19-0.79 mm; 0.28 ± 0.05 mm), the third to the tenth (0.54-0.71 mm; 0.66 ± 0.07 mm), the eleventh reaches (0.51-0.73 mm; 0.77 ± 0.03 mm); frontoclypeal suture membranous, almost straight; clypeus trapezoidal, anterior margin concave, with setae along the margin; mandibles falcate, robust, with setae on the external base; maxillar palpomere ogival and robust, labial palpomere securiform.
Thorax. Pronotum wider (3.95-4.4 mm; 4.04 ± 0.08 mm) than long (2.8-3.4 mm; 3.01 ± 0.27 mm), semicircular, with a longitudinal groove indistinct in the basal half, anterior margin rounded, posterior sinuate, posterior angles straight, sides narrowly explanate, with irregular glandular pores at the front and ordered on the posterior and lateral margins, surface brilliant, abundant pilosity, decumbent; scutellum spatulate, with the posterior margin rounded, surface brilliant, punctate and decumbent pilosity; long elytra, parallel, four and a half times longer (12-13.5 mm; 12.6 ± 0.57 mm) than wide (2.4-2.8 mm; 2.58 ± 0.19 mm), surface rugose, opaque, with two types of pilosity, one relatively long and erect, the other small and procumbent; mesothoracic respiratory spiracles not tubular; long legs, pro, meso and metalegs similar to each other, femurs fusiform, tibiae channeled, a little dilated at the apex, external margin crenulate, two symmetric tibial spurs present in pro, meso and meta legs, tarsomeres laterally compressed, first metatarsomere longer (0.6-0.76 mm; 0.73 ± 0.03 mm) than the next two metatarsomeres together (0.51-0.68 mm; 0.63 ± 0.08 mm), fourth bifid, covering the fifth, claws simple.
Abdomen. Sternites 5-6 longer than the preceding, with stigmatiform pores, posterior margin of sternite six cleaved, the seventh concave, the eighth ojival; posterior margin of pygidium convex; aedeagus short, robust, with symmetrical basal piece (0.67-0.7 mm; 0.68 ± 0.05 mm), as long as lateral lobes (0.66-0.7 mm; 0.67 ± 0.45 mm), with posterior margin concave, lateral lobes apically acute and convergent, median lobe cylindrical, with dorsal part membranous and ventral part with sclerosed base and apical half membranous, dorso-basal excrescences as long, oblique lobes, median orifice apical, lateral lobes narrowing towards the apex, apex blunt and wide (Fig. 3C, D, E View Figure 3 ).
Adult female
(Fig. 4A, B View Figure 4 ) (n = 14). Length: 11.1-20.3 mm; width: 3.2-6.5 mm. Body brownish, except the pronotal disk with a central black spot and two red spots at the sides; procoxae, protrochanters, meso-coxae, meta-coxae, seventh and eighth sternites yellowish; light organ in fifth sternite.
Head. Interocular space flat, more or less parallel, shagreen integument, brilliant and pilose, frons vertical, interantennal distance (0.16-0.37 mm; 0.25 ± 0.10 mm) wider than antennal fossae (0.16-0.37 mm; 0.44 ± 0.16 mm); eyes small, finely faceted, semispherical, longer (0.65-0.94 mm; 0.67 ± 0.25 mm) than wide (0.45-0.76 mm; 0.54 ± 0.15 mm), antennae filiform, short (4.16-5.52 mm; 5.23 ± 0.96 mm), as long as the length of pronotum, without extending beyond the posterior margin of metasternum; scape reaching a length of (0.57-0.64 mm; 0.58 ± 0.34 mm), longer than the two next antennomeres together, the second short (0.2-0.39 mm; 0.37 ± 0.06 mm), from the third to the tenth (0.35-0.58 mm; 0.44 ± 0.07 mm), the eleventh reaches (0.54-0.69 mm; 0.68 ± 0.05 mm); frontoclypeal suture membranous, almost straight; clypeus trapezoidal, anterior margin concave, with setae along the margin; mandibles falcate, robust with setae on the external base; maxillar palpomere ogival and robust, labial palpomere securiform.
Thorax. Pronotum wider (3.27-4.97 mm; 4.21 ± 0.86 mm) than long (2.21-2.6 mm; 2.2 ± 0.2 mm), semicircular, with a longitudinal groove indistinct on the basal half, anterior margin rounded, posterior margin straight, posterior angles straight, sides narrowly explanate, with glandular pores irregular at the front and ordered on the posterior and lateral margins, surface brilliant, pilosity abundant, decumbent, scutellum spatulate, with the posterior margin rounded, surface brilliant, punctate and pilosity decumbent; elytra short, without covering the abdomen, two-and-a-half times longer (4.62-6.5 mm; 5.2 ± 0.62 mm) than wide (1.91-2.71 mm; 2.22 ± 0.42 mm), surface rugose, opaque, pilosity decumbent; divergent in the median margin, epipleura reduced, mesothoracic respiratory spiracles not tubular; legs similar to each other; tibiae and femurs flat, fusiform, tibiae channeled, a little dilated at the apex, external margin crenulate, tarsomeres laterally compressed, first metatarsomere (0.41-0.64 mm; 0.62 ± 0.22 mm) slightly longer than the next two together (0.46-0.58 mm; 0.53 ± 0.06 mm), the fourth bifid, covering part of the fifth, claws simple.
Abdomen. Sternites 5-6 longer than the preceding, without stigmatiform pores, posterior margin of sternite six almost straight, the seventh cleaved, the eighth with a notched; posterior margin of pygidium convex. Internal genitalia with a short and rounded spermatophore-digesting gland, longer than spermatheca, bursa copulatrix with an elongated and weakly sclerotized plate. Ovipositor with valvifers free, two-and-a-half times longer (2.41-3.10 mm; 2.75 ± 0.48 mm) than coxites (1-1.12 mm; 1.06 ± 0.08 mm); coxites divergent posteriorly; styli minute, sclerotized; proctigerplate short with rounded posterior margin, well-sclerotized (Fig. 4C, D, E View Figure 4 ).
Description of pre-imaginal stages.
Egg (Fig. 5A, B View Figure 5 ).
Semispherical shape, whitish, with a diameter of approximately 290-300 µm (Fig. 5A View Figure 5 ). Surface with concavities that differ in size and shape (4-10 µm), evenly distributed, some present in aggregations (Fig. 5B View Figure 5 ). As time elapsed, the surface of the eggs became more transparent, allowing the observation of the larvae before hatching.
Sixth instar larva (Figs 6A, B View Figure 6 , 7A-H View Figure 7 , 8A-G View Figure 8 , 9A-F View Figure 9 ).
Description. Elongate, tapering body, dorso-ventrally flattened, length 12.27-18.18 mm; integument of granular appearance; tergites from protergum to abdominal segment IX divided by sagittal line in dorsal view. Tergites with two lateral pale stripes that run throughout the body to the VIII segment, more sclerotized than the sternites, with clearly visible setae on the posterior margin of tergites VII to X; the last tergum completely dark except the lateral margins paler; anterior margin of the first head segment with two fossae (sensorial or glandular) paler and bigger than the rest of the punctations of the segment. Membranous pleura except for a dark sclerotized area around the spiracles, without apparent setae. The ventral surface is flexible due to the intersegmental membranes. Mesothoracic and abdominal pleural areas of segments I-VIII with bilabiate spiracles.
Head capsule. Prognathous; slightly visible when retracted into prothorax due to the transparency of the protergum; extensible neck membrane covered in extremely short spines forms a two-layer envelope around the head; partially retractable within the prothorax; completely sclerotized, small, wider (0.88-1.54 mm; 1.2 ± 0.27 mm) than long (0.68-1.09 mm; 0.92 ± 0.17 mm), flat, sides almost parallel; stemmata on each side, with an almost transparent spot located posteriorly to the stemmata; clypeus and labrum fused forming the clypeo-labrum covering base of the mandibles in dorsal view; maxillae and labium connate forming maxillolabial complex covering most of the ventral cephalic area; epicranial suture dark, U-shaped, with a very short epicranial stem, frontal arms V-shaped (Figs 7A View Figure 7 , 8A View Figure 8 ). Epipharynx formed by two oval plates, without setae, that project centrally beyond the anterior margin of the head. Hypopharynx with short setation.
Antenna. Trimerous, located on the distal margin of the epicranial plate; partially retractable into the antennal socket; three-segmented, basal antennomere and second antennomere (0.42-0.55 mm; 0.48 ± 0.05 mm) elongated, and a third segment (the flagellum) short (0.24-0.31 mm; 0.26 ± 0.03 mm); adjacent sensorial cone present; basal antennomere with two long setae in the anterior mid, almost entirely covered by moderately dense, second antennomere with long setae close to apex and entirely covered by dense smaller finer setae, third antennomere with long setae from base to apex, with short setae on the anterior margin (Fig. 7B View Figure 7 , 8B View Figure 8 ).
Maxilla. Consisting of five parts, attached to lateral margins labium forming a maxillo-labial complex. Cardo elongate, irregular shape, with four setae in ventral surface, on long setae in posterior margin. Stipes elongated, ventrally covered with erect setae, with three long stout setae placed radially on the ventral apical region. Galea present, with two segments, the first longer and stouter than the apical, which is triangular (Fig. 7C, D View Figure 7 ). Lacinia covered with brush of long setae on outer lateral margin. Maxillae with three-segmented palpi, basal segment long (0.57-0.71 mm; 0.66 ± 0.06 mm) covered by setae in mid-region, segment II wider (0.30-0.40 mm; 0.35 ± 0.04 mm) than long (0.12-0.16 mm; 0.14 ± 0.01 mm); apical segment cylindrical (0.10-0.14 mm; 0.12 ± 0.01 mm) with numerous setae from base to mid region; (Figs 7E, F View Figure 7 , 8C, D View Figure 8 ).
Labium. Closely attached to maxilla, formed by prementum, mentum and postmentum. Prementum heart-shaped, surface covered with numerous short setae and two long setae close apex; labial palpi with two segments, basal palp subquadrate with few setae in mid-region, distal palp conical without setae; mentum with one pair of setae on anterior third and one pair of setae on posterior third; postmentum elongate, slightly sclerotized at the medial base, laterally united by membranes to the cardines; with a setae on each side near the base.
Mandible. Symmetrical, falcate, strongly sclerotized, with an internal channel opening subapically on outer edge. Penicillus well-developed. Retinaculum short and rounded, present only as a blunt protuberance on basal third of the mandible. Densely covered by fine setae on the external margins basely, basal half on inner margin of mandible covered with a brush of stout setae, being longest on the retinaculous protuberance (8E, F); mesal margin serrate.
Thorax. Protergum wider (2.43-3.81 mm; 3.14 ± 0.57 mm) than long (1.54-2.59 mm; 2.11 ± 0.43 mm), subsemicircular, wider posteriorly, rounded at posterolateral corners, covering the retracted head. Meso- and metatergum subrectangular three times wider than long, delimited by a pleural suture elongate barely evident from the laterotergites. Lateral areas of meso and metathorax scarcely sclerotized, composed of two laterotergites, the anterior with a well-developed spiracle on the mesothorax. Episterna extending from the anterior part to the lateral part of the coxae; epimeron forming a little sclerotized stripe, parallel to the coxae.
Legs. Pentamerous, the first pair of forelegs slightly shorter than the second and third. Coxae short (0.76-1.16 mm; 0.98 ± 0.18 mm), cylindric, widely separated at the base, decumbent; coxal-trochanteric membrane reaching about 1/3 of the coxal length. Trochanters pentagonal, joining the femur obliquely (0.51-0.82 mm; 0.71 ± 0.13 mm). Femur narrow and cylindrical in lateral view. Tibiotarsus narrowing distally with stout setae. All legs with a double row of long setae in the inner margin, numerous short setae in the outer margin: pretarsus claw-like with two setae at base (Figs 7G, H View Figure 7 , 8G View Figure 8 ).
Abdomen. Tergites III-IX of similar length (0.86-1.36 mm; 1.09 ± 0.17 mm), width almost constant; segments I-VIII (or I-VII) wider than long, bearing a pair of long stout setae posterolaterally, with laterotergites at each side, with sclerotized plates containing the spiracles; ventral area of segments I-VIII with sternal areas almost squared, slightly pigmented, sternites with two long setae in mid-region; sternal medial area margined by laterosternites - sometimes pigmented, elongate, narrow, and paired, delimited by laterotergites dorsally, and ventrally by a medial sternal plate; ventral area of segment IX with a simple plate, without area differentiation; light organ present and segment VIII indistinct; abdomen ending with a series of eversible filaments (pygopodia) bifurcate at the apex, at least 30 pygopodia arise from 12 basal stalks which may branch more than once (the dorso and ventrolateral stalks branch into three); densely packed recurved hooks occur on the ventrolateral surface of each exerted pygopod and completely covering at apex, with toothed scales on the dorsolateral surface only on anterior half. (Fig. 9A-G View Figure 9 ).
Third instar larva (Fig. 6C, D View Figure 6 ).
Description. Similar to sixth instar. Length 11.45-13.78 mm. Head capsule. Wider (0.82-0.96 mm; 0.92 ± 0.05 mm) than long (0.57-0.85 mm; 0.71 ± 0.12 mm). Antenna. Basal antennomere and second antennomere (0.28-0.35 mm; 0.32 ± 0.02 mm), and a third segment (the flagellum) (0.15-0.21 mm; 0.18 ± 0.02 mm). Maxilla. Maxillae with three-segmented palpi, basal segment long (0.34-0.54 mm; 0.43 ± 0.07 mm) covered by setae in mid region, segment II wider (0.30-0.43 mm; 0.36 ± 0.06 mm) than long (0.12-0.17 mm; 0.14 ± 0.02 mm); apical segment cylindrical (0.10-0.13 mm; 0.11 ± 0.01 mm). Thorax. Protergum wider (1.36-1.53 mm; 1.4 ± 0.06 mm) than long (1.18-1.68 mm; 1.3 ± 0.20 mm), trapezoidal. Legs. Coxae short (0.77-0.97 mm; 0.86 ± 0.08 mm), femur obliquely (0.43-0.60 mm; 0.52 ± 0.07 mm). Abdomen. Tergites III-IX (0.68-0.85 mm; 0.77 ± 0.045 mm) ventral area of segments I-VIII with sternal areas almost squared, slightly pigmented, sternites with two long setae in mid-region.
First instar larva (Fig. 6E, F View Figure 6 ).
Description. Similar to sixth instar. Length 3.72-8.80 mm; after hatching, the first instar body does not appear sclerotized to the degree found in later instars. Head capsule. Wider (0.48-0.72 mm; 0.6 ± 0.10 mm) than long (0.24-0.51 mm; 0.38 ± 0.12 mm), s (Figs 6A View Figure 6 and 7A View Figure 7 ). Antenna. Basal antennomere and second antennomere (0.12-0.28 mm; 0.19 ± 0.06 mm) elongated, and a third segment (the flagellum) short (0.08-0.17 mm; 0.12 ± 0.03 mm). Maxilla. Maxillae with three-segmented palpi; basal segment long 0.24-0.47 mm; 0.31 ± 0.08 mm) and well-defined, segment II wider (0.12-0.17 mm; 0.15 ± 0.01 mm) than long (0.05-0.07 mm; 0.06 ± 0.007 mm); apical segment (0.03-0.047 mm; 0.037 ± 0.007 mm). Labium. Postmentum elongate, slightly sclerotized at the medial base, laterally united by membranes to the cardines; with a setae on each side near the base.
Thorax. Protergum wider (0.73-1.47 mm; 0.94 ± 0.21 mm) than long (0.51-0.75 mm; 0.53 ± 0.09 mm). Legs. Coxae short (0.44-0.65 mm; 0.53 ± 0.08 mm), femur obliquely (0.21-0.34 mm; 0.27 ± 0.05 mm). Abdomen. Tergites III-IX (0.31-1.2 mm; 0.74 ± 0.28 mm).
Pupa, male (Fig. 10A, B View Figure 10 ).
Length 17-23 mm; width 6-7 mm. Body elongate, curved, ventrally concave, pale yellowish (sternites I-VIII slightly pigmented at the ends).
Head. Totally covered by the pronotum in dorsal view. Large eyes, located at the sides of the head; antennae in front of the eyes, nearer the frontal center, mouthparts visible in ventral view.
Thorax. Pronotum wider than long, semicircular, totally covering the head. Meso and metanotum shorter, subrectangular, bearing the elytra sidewards. All pairs of legs free, visible in ventral view. Spiracles present in the pleural areas of mesothorax.
Abdomen. Abdominal segments subrectangular, wider than long, spiracles present on abdominal pleural areas of segments I-VIII. Light organ on sternites V-VI.
Life cycle (Fig. 11 View Figure 11 ).
In their natural habitat, adults of P. extensus are active from early July, when the first males can be observed. Bioluminescent activity begins at dusk, at approximately 20:00 h, and diminishes considerably an hour later. Male flight does not exceed 2 m in height. Females are brachypterous and perch in the undergrowth approximately 50 cm from the ground. Males flash every 4.5 seconds, flying in an arc when illuminated. When males detect a female, they wait for an intense flash as a response, which is brief. The flash intervals are of 10 to 20 seconds. Males react by flying lower and towards the female. Groups of 3 to 5 males commonly compete with each other to get the female first, to mate with her. Two types of competition were observed among males: 1) a mating ball: four or more males cover the copulating pair and try to dislodge the copulating male to gain access to the female, and 2) males using their pronotum as a lever to pry a copulating male from the female. In the laboratory, copulation was observed to last from between 2 to more than 4 hours.
During oviposition, females bend their abdomen and place the apical part of it on the substrate. Eggs are laid superficially or buried, randomly distributed, individually, or in groups (up to aggregates of 50). The number of eggs deposited by each female varied from three to 198. Eggs emit a faint bioluminescence since they are oviposited, which is only perceptible to the human eye in complete darkness. In total, 956 eggs from 13 females were obtained.
Under lab condition P. extensus completed its development in approximately 12 months, from oviposition to imago. The egg stage under laboratory conditions had a duration of 11 to 70 days, with mortality of n = 144 eggs (15%).
Photinus extensus undergoes six similar larval instars that differ in both size and color (Fig. 4 View Figure 4 ). Cannibalism among larvae during rearing was not observed. The only food larvae consumed was the earthworms provided. There was no synchronization among larvae during the progression of larval instars, which started at the end of August until the beginning of July. In captive conditions, the process of ecdysis from one stage to the other varied among individuals. The first larval instar had a duration of 14 to 153 days, where mortality was 60% (n = 491) among the eggs that hatched. The second larval instar had a duration of 14 to 172 days, with mortality of 61% (n = 199). The third larval instar had a duration of 15 to 140 days; mortality was 71% (n = 87). The fourth larval instar had a duration of 17 to 140 days, with a mortality of 52% (n = 20). The fifth larval instar had a duration of 24 to 192 days (n = 18) and the last larval instar had a duration of 53 days (n = 8). Pupation had a duration of 7 days in July, and according to the observations in the field, pupae were found under pyroclastic rocks.
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