Macrostemum brasiliense ( Fischer, 1970 )

Pes, Ana M., Desidério, Gleison R., Barcelos-Silva, Patrik & Hamada, Neusa, 2019, A new species of Macrostemum Kolenati, 1859 from Brazilian Amazon and the immature stages of M. brasiliense (Fischer, 1970) (Trichoptera: Hydropsychidae), European Journal of Taxonomy 534, pp. 1-20 : 9-17

Macrostemum brasiliense ( Fischer, 1970)

Figs 5–9

Macrostemum brasiliense ( Fischer, 1970) : 242 [nomen novum for Phryganea maculata Perty, 1833 , preoccupied in Phryganea by Phryganea maculata Donovan, 1813 , which is now a synonym of Hydropsyche instabilis (Curtis, 1834) ]. — França et al. 2013: 309 [♂; wings; status]. — Paprocki & França 2014: 29 [checklist]. — Holzenthal & Calor 2017: 154 [catalog].

Phryganea maculata – Perty 1833: 129 [Type locality: Brazil, inter St. Pauli civitatem et Villam riccam; ZSM; ♂].

Macronema tuberosum – Ulmer 1905: 82 [Type locality: Bahia, Brasilia; NMW; ♂; wings]. — Ulmer 1907a: 78, pl. 3 [♂; wings]. — Ulmer 1907b: 165 [distribution]. — Flint 1966: 7, pl. 1 [lectotype; ♂; wings]. — Ulmer 1913: 408 [distribution]. — Fischer 1963: 199 [bibliography, checklist]. — Burmeister 1983: 273 [to synonym of Macronema maculatum ].

Macronema maculatum – Ulmer 1907a: 79 , pl. 3 [wings; ♀]. — Ulmer 1913: 395 [♂; distribution]. — Fischer 1963: 190 [bibliography]. — Flint & Bueno-Soria 1982: 358 [to Macrostemum ]. — Burmeister 1983: 273 [type situation]. — Burmeister 1989: 259 [lectotype; ♂].

Macrostemum maculatum – Flint et al. 1999: 68 [catalog]. — Paprocki et al. 2004: 8 [checklist]. — Calor 2011: 321 [checklist]. — Barcelos-Silva et al. 2012: 1278 [distribution]. — Dumas & Nessimian 2012: 13 [checklist]. — França et al. 2013: 309 [to synonymy].

Material examined

BRAZIL: • 1 ♂; Minas Gerais, Poços de Caldas, Fazenda de Eucalipto, Second-order stream; 21º53′33.2″ S, 46º33′03.8″ W; alt. 1327 m; 14–15 Sep. 2017; G.R. Desidério, E.P. Brandão and L.M. Fusari leg.; INPA • 10 larvae, 1 pharate pupa ♂; São Paulo, Salesópolis, Estação Biológica Boracéia, Córrego Venerando ; 23°39′04.7″ S, 45°53′28.3″ W; alt. 864 m; 22 Sep. 2017; G.R. Desidério, E.P. Brandão and L.M. Fusari leg.; INPA • 4 ♂♂; São Paulo, Salesópolis, Estação Biológica Boracéia, tributary of the Córrego Venerando stream; 23º39′13.2″ S, 45º53′24.4″ W; 20–22 Sep. 2017; G.R. Desidério, E.P. Brandão and L.M. Fusari leg.; INPA .

Description

Larva (5 th instar) ( Figs 6–8 )

Length 19.6–21.2 mm (mean = 20.3 mm, SD = 0.66 mm, n = 5).

HEAD. Subrectangular and flattened in dorsal view, with anterior margin 1.5 × wider than posterior margin ( Fig. 6A ); dark-brown except for darker anterodorsal region; each stemmata surrounded by a pale-yellow oval spot; muscle scars inconspicuous. Dorsolateral carina prominent passing above eyes, extending to posterior region, diverging from the frontoclypeal suture ( Fig. 6A, C ). Chaetotaxy consisting of #2, #3, #7, #9, #11, #13, #14, #16, #17 [dorsal setae], #12 [lateral setae], #8, #10 [ventral setae]. Primary setae mostly long, thick and pale brown ( Fig. 6 A–C). Frontoclypeus with anterior margin straight, symmetrical ( Fig. 6A ). Labrum golden-brown, with large membranous basal region bearing 2 transverse sclerites adjacent to frontoclypeus; anterior margin protruding medially, with dense fringe of pale-yellow, hairlike setae over its entire length and a row of short, brown clavate setae; laterally with a pair of pectinate brushes of setae, long, yellowish-brown and anteriorly directed; mesodorsally surface with short, stout brown setae and one pair of long, parallel, submarginal setae ( Fig. 6E ). Mandibles asymmetrical, each external margin with pale, long, thin setae; left mandible with 1 obtuse molar tooth, 1 bilobed, mesal tooth, 2 subequal acute subapical teeth, 1 acute, apical tooth, 1 apicodorsal tooth; right mandible with 1 obtuse molar tooth, 1 obtuse mesal tooth, 1 obtuse subapical tooth, 1 acute apical tooth, 1 apicodorsal tooth; both mandibles without dorsomesal tuft of thin setae ( Fig. 6F ). Lateral sides of head with series of pale-brown muscle scars located posteriorly to occipital margin at posterior tentorial pit ( Fig. 6C ). Genae located ventrally, each with conspicuous patch of strongly marked, transverse stridulatory lines; widely separated at ⅓ anterior, gradually turning more closely-spaced posteriorly; pale-brown mark covering stridulatory lines and slightly narrowing to posterior region; muscle scars oval and pale grouped on posterior half and scarcely discernible ( Fig. 6B, D ). Submentum trapezoidal, large; anterior margin slightly accentuated medially, with long, dark anterolateral setae ( Fig. 6B ). Ventral ecdysial suture absent anteriorly on the right side; anterior ventral apotome subtriangular, wider than long; posterior ventral apotome triangular, minute, longer than wide ( Fig. 6D ).

THORAX.Nota sclerotized and covered with short, thin, brown, acuminate peg-like setae, mixed with long, slender, hair-like setae. Pronotum divided by longitudinal ecdysial line, dark-brown, muscle scars barely visible, grouped posterolaterally and with anterolateral pronotal margin slightly concave ( Fig. 7 A–B). Meso- and metanotum not divided by ecdysial lines, pale-brown, darker midlaterally, lateral diagonal grooves slightly visible, muscle scars barely visible, grouped posterolaterally ( Fig. 7B ). Prosternum without gills, broadly transverse, without triangular, posteromesal sclerite ( Fig. 7C ); mesosternum without gills; metasternum with 2 pairs of ventrolateral gills, each with long stalk and few regularly distributed lateral filaments ( Fig. 8 ). Foretrochantin triangular, tapered to apex with a row of numerous median, stout, brown, acuminate peg-like setae ( Fig. 7D 1 ). Foreleg dark-brown, shorter than mid- and hind legs; foreleg coxae with anterodorsal process slightly pronounced; with four long, dark, thick setae on posterodorsal region, ventral margin covered with numerous short, pale, slender setae and two long dark thick setae posteriorly; trochanters and femora each with numerous pale-yellow, long, slender setae on ventral margin, mixed with row of 11–13 dark, long, slender setae; femora each with slender, digitate basomesal process on internal surface; tibiae and tarsi with dense fringe of pale-yellow, medium-sized, slender setae on dorsal margin and row of thick setae on ventral margin ( Fig. 7D 1 ). Mid- and hind legs paler, similar in size, shape, and structure; femora each with numerous medium-sized, pale-yellowish, slender setae on ventral margin, mixed with 4 dark, long, slender setae, and 2 dark, long apicodorsal setae; tibiae and tarsi with numerous medium-sized pale-yellow, slender setae on ventral margin, and dark, long, slender dorsal setae ( Fig. 7D 2 –D 3 ).

ABDOMEN. Abdominal segments densely covered with long, dark, thin, hair-like setae; with slightly depression on cuticle. Lateral fringe of setae absent ( Fig. 7A ). Ventral gills on abdominal segments I–VII; ventrolateral gills on abdominal segments II–III; lateral gills on abdominal segments I–VII; shape and position of gills as indicated in table of Figure 8 . Sternum VIII with 2 small sclerites; each sclerite with 5–6 medium-sized, dark, slender setae ( Fig. 7E ). Segment IX with small, dorsolateral plate bearing 2 long, dark, slender setae, and with a row of long, dark setae laterally ( Fig. 7A ). Sternum IX with 2 subrectangular sclerites, longer than wide, bearing moderate-sized, pale-yellowish, spikelike setae with spines emanating from prominent sockets; each sclerite with 12–14 long slender, dark setae on external and posterior margin ( Fig. 7E ). Anal prolegs each with lateral sclerite bearing tuft of numerous, long, hair-like dorsal setae; anal claws stout, right-angled, each with 1 bent, simple, long, dark, ventrobasal seta ( Fig. 7A, E ).

LARVAL RETREAT. The larval retreat of M. brasiliense is similar to that of Macrostemum sp. described by Sattler (1963, 1968) and illustrated in Pes et al. (2005) from an unidentified species of Brazilian Amazonia, with an elaborate net for fine particle capture.

Pupa ( Fig. 9 )

Body length 16.7 mm (n = 1).

HEAD. Labrum with anterior margin rounded; anteromesal region without setae; basolateral lobes each with 2 medium-sized setae ( Fig. 9B ). Mandibles asymmetrical, broad basally, curved mesally, tapering to apex, each with long setal brush basolaterally; inner margin with acute teeth mesally, 3 on both mandibles, and apical half of mandibles finely serrated ( Fig. 9C ). Frons faces anteriorly with oval protruding lobe, mesally bilobed bearing 9–11 long, dark setae and one medium-sized seta on each lobe, posteriorly with 8 long, dark setae. Basal antennal article with 5 medium-sized, brown setae ( Fig. 9B ).

THORAX. Pale yellow, with dark spots laterodorsally. Tibia and tarsus of midleg broad and flattened, with well-developed lateral fringes of setae ( Fig. 9A ).

ABDOMEN. Numerous moderate-sized, yellowish-brown, spike-like setae covering abdominal terga II, III on its posterior portion, and a file of long, thin, dark, hair-like setae on tergum IV in its entire posterior portion ( Fig. 9A ). Lateral fringe absent. Abdominal terga with pairs of anterior hook plates (a) on segments III–VIII with hooks directed posterad; pair of posterior hook plates (p) on segment III with hooks directed anterad; hook-plate pair IIIa with 2–3 pointed, stout hooks; hook-plate pair IIIp with 56–60 sharply pointed, small hooks; hook-plate pair IVa each with 2 pointed, stout hooks; hook-plate pair Va with 2 pointed, stout hooks and 1–2 mesal, smaller; hook-plate pair VIa each with 1 bifid hook, 1 pointed, stout hook and 1 minute; hook-plate pair VIIa with 2 pointed, stout hooks and 1 smaller; hook-plate pair VIIIa each with 2 pointed, stout hooks ( Fig. 9D ). Apical processes of segments IX–X long, slender, widely separated, each with 23–24 long lateral, setae on external margin and 6–9 long subapical setae on internal margin ( Fig. 9E ).

PUPAL RETREAT. Inside the larval retreat, the 5 th instar constructs a tubular case of resistant sand covered with silk, with a small opening in the posterior region; in the anterior region the opening is closed with a cover of sand where the larva weaves the pupal cocoon, it is similar to that of the Amazonian undetermined species described by Sattler (1963).

Taxonomic remarks

In the larval stage, M. brasiliense is similar to M. ulmeri by the prominent dorsolateral carina extending to posterior region, diverging from the frontoclypeal suture. Both can be distinguished from other species in the genus with known immatures like the Nearctic M. carolina (Banks, 1909) , M. transversum (Walker, 1852) and M. zebratum (Hagen, 1861) , which have carina closed passing over the posterior region from the frontoclypeal suture. Additionally, M. brasiliense is characterized by the dark-brown head with darker anterodorsal region; frontoclypeus with anterior margin straight; left mandible with 1 obtuse molar tooth and 1 bilobed mesal tooth; right mandible with 1 obtuse mesal tooth and 1 obtuse subapical tooth; genae with transverse stridulatory lines widely separated at anterior ⅓, transition to closely-spaced posterior lines gradual; submentum with anterior margin convex with slight projection medially, with long, dark anterolateral setae; mesosternum without gills; foreleg coxae with anterodorsal process slightly pronounced; ventral gills on abdominal segments I–VII, ventrolateral gills on abdominal segments II–III and lateral gills on abdominal segments I–VII.

The pupa of M. brasiliense is similar to that of M. ulmeri by abdominal terga with pairs of anterior hook plates on segments III–VIII, with stout hooks directed posteriorly, and pair of posterior hook plates on segment III with hook directed anteriorly. However, M. brasiliense has hook-plate pair IIIa and IVa each with 2–3 and 2 pointed hooks, respectively, and 56–60 sharply pointed, small hooks directed anteriorly of the posterior hook plates, while M. ulmeri has 3 pointed hooks on each hook-plate pair IIIa and IVa and 23–35 sharply pointed, small hooks on posterior hook plates.

Bionomics

This species is commonly found in Brazilian Atlantic Forest ( Santos et al. 2018). In the present study it was collected in small mountain streams in rain forest reserve (Estação Biológica de Boracéia) in Salesópolis municipality, São Paulo state, at an elevation of 864 m a.s.l. ( Fig. 5 A–B) and in an extensive area with Eucalyptus spp. ( Myrtaceae ) plantations, in Poços de Caldas municipality, Minas Gerais state, at an elevation of 1327 m a.s.l. ( Fig. 5A ).

Distribution

Brazil (Bahia, Minas Gerais, Rio de Janeiro, and São Paulo states).

Figures

Fig. 5. Collection sites of Macrostemum araca sp. nov. and Macrostemum brasiliense (Fischer, 1970) and general views of some of the sampled streams and rivers. A. A map showing the collection sites of M. araca sp. nov. and M. brasiliense in the Amazon and Atlantic Forest, respectively. B. Córrego (stream) Venerando, São Paulo, collection site of M. brasiliense. – C–E. collection sites of M. araca sp. nov. C. Igarapé da (stream) Cobra, Amazonas. D. Igarapé (stream) do Jabuti, Amazonas. E. Rio (river) Aracá, Amazonas.

Fig. 6. Macrostemum brasiliense (Fischer, 1970), larva. A. Head, dorsal view. B. Head, ventral view. C. Head, left lateral view. D. Stridulatory lines of genae, ventral view. E. Labrum, dorsal view. F. Mandibles, dorsal view. Scale bars = 0.2 mm.

Fig. 7. Macrostemum brasiliense (Fischer, 1970), larva. A. Larval habitus. B. Thoracic nota, dorsal view. C. Prosternum sclerite. D 1. Foreleg. D 2. Midleg. D 3. Hindleg. E. Sternum VIII, IX and anal prolegs, ventral view. Scale bars: A = 1 mm; B = 0.5 mm; D 1 –D 3, E = 0.2 mm.

Fig. 8. Macrostemum brasiliense (Fischer, 1970), larva; gill formula (MS = mesothorax; MT = metathorax; i–viii = abdominal segments; V = ventral gills; VL = ventrolateral gills; L = lateral gills).

Fig. 9. Macrostemum brasiliense (Fischer, 1970), pupa. A. Pupal habitus, dorsal view. B. Head, frontal view. C. Mandibles, dorsal view. D. Hook plates, dorsal view (III–VIII = abdominal segments, a = anterior, p = posterior). E. Abdominal segments IX–X, dorsal view. Scale bars: A = 2 mm; B, E = 0.05 mm; C–D = 0.2 mm.

Fig. 1. Macrostemum araca sp. nov., adult male. A. Dorsal habitus. B–C. Head, dorsal and frontal views. D. Forewing (holotype). E. Forewing, variation in the apical area (paratype). F. Hindwing (holotype). G. Process of sternite V. Scale bars: A, D–F = 2 mm; B–C = 0.5 mm.

Fig. 2. Macrostemum araca sp. nov., adult male. A. Venation of the forewing (holotype). B. Venation of the hindwing (holotype). Scale bar = 2 mm.

Fig. 3. Macrostemum araca sp. nov., male genitalia. A. Lateral view. B. Dorsal view. C. Ventral view. D–E. Phallus, lateral view. F–G. Phallus, dorsal view. H–I. Phallus, ventral view. Scale bars: A–D = 0.2 mm; E–I = 0.1 mm.