Anachauliodes laboissierei (Navás, 1913)

Tu, Yuezheng, Hayashi, Fumio & Liu, Xingyue, 2019, First description of the larvae of the fishfly genus Anachauliodes Kimmins, 1954 (Megaloptera: Corydalidae: Chauliodinae), Zootaxa 4700 (2), pp. 270-278 : 272-276

Larval description of Anachauliodes laboissierei (Navás, 1913)

Description of the first-instar larva. Head. Almost entirely brown, posteriorly with reddish brown markings. Vertex with several macrosetae, laterally with one seta on each side ( Fig. 2A ). Stemmata and adjacent area dark reddish brown. Mandibles, maxillae and labrum yellow. Mandible with four teeth shaped like those of the late-instar larvae ( Fig. 2C ). Maxilla with a few slender setae, maxillary palp three-segmented ( Fig. 2D ). Antenna 5-segmented, a long seta present on third segment, with a macroseta at adjacent area ( Fig. 2E ).

Thorax. Prothorax wider than long, with several dark setae. Meso- and metanotum immaculate, with scattered setae ( Fig. 2A ). Legs short and stout, yellowish brown, all segments with long, slender setae. Tarsal claws differing in length, length of longer one approximately 2× shorter one ( Fig. 2F ).

Abdomen. Yellowish brown, segments I–VIII with a pair of lateral filaments. Lateral filaments soft, with several setae on apex. Each lateral filament with a tenuous, bent trachea inside, which fused to trachea inside abdomen ( Fig. 2G ). A pair of respiratory tubes present on posterior margin of abdominal segment VIII. Respiratory tube distinctly shorter than lateral filament, narrowed distad ( Fig. 2H ). Length of right respiratory tube equal to that of left one ( Fig. 2H ). Slender, curved claws present at tip of anal prolegs, with long, slender setae (longer than claws) basally ( Fig. 2H ).

Measurement (n = 10). Head width, 0.437 ± 0.018 mm. Head length, 0.483 ± 0.012 mm. Prothorax width, 0.404 ± 0.017 mm. Prothorax length, 0.282 ± 0.009 mm. Total body length, 1.933 ± 0.070 mm. Right respiratory tube length, 0.090 ± 0.004 mm and left respiratory tube 0.089 ± 0.002 mm.

Description of the late-instar larva. Head. Rounded, length similar to width ( Figs. 3A, B ; 4A, B ). Almost glabrous with a few macrosetae laterally, entirely reddish brown. A pale-yellow band surrounding six stemmata on each side. Anterior tentorial grooves dark, almost black. Antennae five-segmented, yellow ( Fig. 4E ). Labrum apparently wider than long, with slender setae along anterior margin ( Fig. 4A ). Anteclypeus yellowish brown, pale along margins, with longitudinal white stripes on adjacent area of left and right margins. Mandible dark reddish brown with four teeth. Three preapical teeth truncate, wide, similar in length. Apical tooth approximately 1.5× length of preapical tooth ( Fig. 4C ). Maxillae yellowish brown. A row of long, yellow setae along inner margin of stipes present. Maxillary palp yellow, with five segments. Labial palp three-segmented, basal segment yellowish brown, but remaining segments yellow. Mentum yellowish brown, with lateral and posterior margins darker ( Fig. 4D ). Gula reddish brown with several slender, pale setae, anterolaterally distinctly protruding into pair of lobes (= submental apohysis in Beutel & Friedrichi 2008), which are dark brown, each lobe distally not concaved. Occipital region reddish brown, immaculate ( Fig. 4A ).

Thorax. Prothorax subquadrate, slightly wider than long. Pronotum yellowish brown to reddish brown, with several dark or pale markings medially. Margins yellowish brown, adjacent region with sparse macrosetae. Prosternum reddish brown, darker than pronotum, with macrosetae on margins. Cervix yellow, with six longitudinal white stripes. Anterior margin of prosternum similar to cervix in color, with four longitudinal white stripes medially ( Fig. 4B ). Meso- and metathorax short, distinctly wider than long. Length of mesothorax plus metathorax shorter than prothorax. Mesonotum and metanotum yellowish brown with large yellow markings, bearing macrosetae on margins ( Fig. 3A ). Legs short, yellow, laterally covered by long, yellow setae. Coxae approximately as long as femora. Trochanter, tibiae and tarsi similar in length ( Fig. 4F, G, H ).

Abdomen. 10-segmented, longer than head plus thorax, smooth; terga purplish brown, with numerous yellowish dots denser at middle; sterna pale brown with dense yellowish dots similar to terga, and each sternum with a dark spot medially ( Fig. 3A ). Abdominal segment I–VIII bearing slender, distally tapering lateral filaments, each lateral filament with sparse setae ( Figs. 3A, B ; 4K ). Abdominal segment VIII with a pair of different-length respiratory tubes posteriorly. Longer respiratory tube present either on right or left side, varying among individuals ( Fig. 4I, J ). Respiratory tubes yellowish brown and rugose ( Fig. 4M ). Abdominal segment X with a pair of yellowish anal prolegs; each proleg with a short lateral filament and a pair of claws ( Fig. 4L ).

Measurement (n = 4). Head width, 6.32 ± 0.40 mm. Head length, 6.39 ± 0.64 mm. Prothorax width, 7.60 ± 0.71 mm. Prothorax length, 7.13 ± 0.98 mm. Total body length, 38.30 ± 11.17 mm. Respiratory tube length, 14.33 ± 2.13 mm in longer one and 8.52 ± 1.08 mm in shorter one.

Remarks. Compared with the late-instar larvae, the first-instar larvae of A. laboissierei have relatively longer setae dorsally on head and thorax. In addition, the respiratory tubes on abdominal segment VIII in the first-instar larvae are short and cone-shaped with the left and right tubes equal in length, whereas those in the late-instar larvae are much longer of different lengths of the right and the left respiratory tubes.

Among all known larvae of Chauliodinae , only larvae of Anachauliodes Kimmins, 1954 and the Nearctic Chauliodes have a pair of long, different-length right and left respiratory tubes on abdominal segment VIII ( Cuyler 1958; Bowles & Sites 2015), which differs from the larvae of the other fishfly genera. The described larvae of Apochauliodes Theischinger, 1983 , Dysmicohermes Munroe, 1953 , Neochauliodes van der Weele, 1909 , Nigronia Banks, 1908 , Parachauliodes van der Weele, 1909 , Platychauliodes Esben-Petersen, 1924 , Taeniochauliodes Esben-Petersen, 1924 as well as the Archichauliodes subgenus Riekochauliodes Theischinger, 1999 have short respiratory tubes ( Evans 1972; Contreras-Ramos & Harris 1998; Theischinger 1999; Liu et al. 2011, 2013; Bowles & Sites 2015; Jung et al. 2015; Shimonoya 2019), whereas in the larvae of some species of Madachauliodes Paulian, 1951 , Neohermes Banks, 1908 , Orohermes Evans, 1984 , Protochauliodes van der Weele, 1909 and the subgenus Archichauliodes van der Weele, 1909 respiratory tubes are much short and just protruded from the abdominal surface slightly ( Evans 1972; Theischinger 1999; Liu et al. 2014; Bowles & Sites 2015; Camacho & Contreras-Ramos 2018).

Cephalic structures can be used to distinguish some larvae of Megaloptera ( Baker & Neunzig 1968; Theischinger 1999; Azevêdo & Hamada 2007; Jung et al. 2015; Camacho & Ramos 2018). In Chauliodinae , each anterior lobe of gula (= submental apohysis in Beutel & Friedrichi 2008) of A. laboissierei and the described larvae of Apochauliodes , Archichauliodes , Chauliodes , Madachauliodes and Taeniochauliodes distally not concaved, whereas those of Neochauliodes , Neohermes , Parachauliodes and Platychauliodes distinctly concaved distally and those of Protochauliodes indistinctly concaved distally ( Theischinger 1999; Beutel & Friedrich 2008; Murray 2008; Liu et al. 2011, 2013, 2014; Jung et al. 2015). Many fishfly larvae can be also distinguished by the characteristics of the mentum. The sclerotized region of mentum is distinctly larger in the described larvae of Apochauliodes , Archichauliodes , Madachauliodes , Neochauliodes , Parachauliodes , Platychauliodes , Protochauliodes and Taeniochauliodes than that in A. laboissierei , Chauliodes and Neohermes ( Theischinger 1999; Beutel & Friedrich 2008; Murray 2008; Liu et al. 2011, 2013, 2014; Jung et al. 2015). Additionally, the larvae of A. laboissierei have indistinct setation on the lateral portions of head, those of some species of Apochauliodes , Archichauliodes , Neochauliodes , Parachauliodes , Platychauliodes and Protochauliodes have distinctly long, slender setae laterally on head ( Theischinger 1999; Beutel & Friedrich 2008; Liu et al. 2011; Jung et al. 2015).

Figures

FIGURE 2. First-instar larva of Annachauliodes laboissierei (Navás, 1913). A. Head and thorax, dorsal view; B. Labrum; C. Mandible; D. Maxilla; E. Antenna; F. Legs, fl = foreleg, ml = midlegs, hl = hindlegs; G. Lateral filaments on abdominal segments V–VIII; H. Abdominal segement VIII, rt: respiratory tubes. Scale bars for A, F = 0.2 mm; scale bars for B, C, D, E, G, H = 0.1 mm.

FIGURE 3. Late-instar larva of Anachauliodes laboissierei (Navás, 1913). A. Habitus, dorsal view; B. Habitus, ventral view. Scale bar = 10.0 mm.

FIGURE 4. Body structures of the late-instar larvae of Anachauliodes laboissierei (Navás, 1913). A. Head and thorax, dorsal view; B. Head, ventral view; C. Right mandible; D. Left maxilla; E. Right antenna; F. Right foreleg; G. Left midleg; H. Left hindleg; I. Respiratory tubes of larva; J. Respiratory tubes of larva (specimen different from previous one); K. Part of lateral filament on abdominal segment VIII; L. Left anal proleg; M. Part of respiratory tube. Scale bars for A, B, I, J= 5.0 mm; scale bars for C, D, E, K, L, M = 1.0 mm; scale bars for F, G, H = 0.5 mm.