Porphyrosela arachisella Moreira & Becker, 2022

Fochezato, Júlia, Brito, Rosângela, Gonçalves, Gislene L., Specht, Alexandre, Becker, Vitor O. & Moreira, Gilson R. P., 2022, Description of Porphyrosela arachisella sp. nov. (Lepidoptera: Gracillariidae), the first report of Lithocolletinae for Brazil, Zootaxa 5165 (3), pp. 387-404 : 389-398

Porphyrosela arachisella Moreira & Becker sp. nov.

Figs 1–8

Type material. MALE HOLOTYPE: BRAZIL: DF, Brasília , gardens of Federal Senate, 13.ix.2018, pinned-dried, ex. larvae mining on Arachis pintoi leaflets, Julia Fochezato coll., deposited in LMCI collection, under accession code 344-67 . Paratypes: pinned-dried adults; same data collection as holotype: seven males ( LMCI 344-49 to 51 , 56 , 58 , 70 and 76); eight females ( LMCI 344-52 , 55 , 57 , 59 , 61 , 63 , 65 , 69 ); all deposited in LMCI collection, except LMCI 344-56 , 58 , 63 , 65 which were donated to VOB .

Dissected adults: same collection data as the holotype: genitalia on slides, 5 males ( LMCI 344-34 A, 34B, 36A, 71), 7 females ( LMCI 344-34 C, 36B, 36C, 72, 74, 75, 77). Immature stages: fixed in Dietrich´s fluid, preserved in 70% ethanol , same collection data as the holotype: three leaf fragments with attached eggs ( LMCI 344-37 ) ; 70 sap-feeding larvae ( LMCI 344-4 ) , 60 tissue feeding larvae ( LMCI 344-5 ) , 15 pupae ( LMCI 344-6 ) .

Other adult specimens examined: Pophyrosela arachisella sp. nov - GO, Goiás, em. 15–25.vi.1976, 52 pinned dried, ex. larvae mining on Arachis pintoi leaflets (Becker 19924) ( VOB). Porphyrosela minuta Clarke – EMBRAPA Pecuária Sul, Bagé, RS, pinned-dried, one male and one female ( LMCI 304-03), with genitalia on slides, ex. larvae mining Trifolium repens leaflets, Gilson R.P. Moreira, 9.ix.2016, deposited in LMCI collection, under accession codes 304-01 and 304-03, respectively.

Diagnosis. Porphyrosela arachisella sp. nov. is morphologically similar to P. desmodiella and P. minuta , from which it can be separated by a conjunction of morphological characters. The adult of P. arachisella differs from both species by possessing forewings with four costal and three dorsal white strigulae. Rarely the basal strigulae are partially fused mesally, forming a transversal fascia as in P. desmodiella and P. minuta . When this is the case, such a transverse fascia is always followed in P. arachisella not by a second fascia but by a pair of well-separated strigulae slightly beyond the middle of the forewing. The second fascia appears either perpendicular to the wing margin or in opposite direction from the basal fascia in P. desmodiella and P. minuta , respectively (Betancourt & Scatoni 2007; Eiseman et al. 2017). In contrast, the forewing of P. arachisella has the two basal pairs of strigulae outwardly oblique, aligned parallel to each other, particularly in the females. The new species is distinguished further from P. desmodiella by the presence of a black terminal line on the forewing, also found in P. minuta . However, P. minuta and P. desmodiella lack the penultimate costal strigula ( Clarke 1953; Betancourt & Scatoni 2007; Eiseman et al. 2017) that is found in P. arachisella , as already noted.

Male genitalia are similar to those of P. minuta by possessing a blunt distal outward margin of valvae, which is bumped in P. desmodiella ( Vári 1961, Pl. 49, fig. 6). Also, by having cornutus in the vesica, which is absent in P. desmodiella . This structure consists of a slightly curved, lightly sclerotized hook in P. arachisella , but is much stronger, looking like a hammer in P. minuta . The saccus is short and stout, with an acute apex in P. arachisella . To the contrary, it has a narrower basal portion and a dilated apex in P. minuta .

There is no detailed description available for larvae and pupae of P. desmodiella and P. minuta , which impedes the corresponding diagnosis at such stages. Notwithstanding, up to now mines of P. arachisella have only been found on Arachis pintoi , a plant not reported as a host for the other two species ( De Prins & De Prins 2022). Contrary to those of P. desmodiella (see Eiseman et al. 2017), mines of P. arachisella are formed on the upper surface of the leaves. They are similar to those of P. minuta , but can be easily distinguished from them by the grouped, side by side attached eggs, either under development or represented by empty chorions, usually three per cluster in P. arachisella . They are laid isolated in the case of P. minuta (Betancourt & Scatoni 2007) .

Description.

Male adult ( Figs 1A–B, D–G ). Forewing length: 1.51–2.08 mm (n = 7).

Head: Vertex tufted with short ochreous, distally furcated, piliform scales; frons smooth, covered with metallic shiny scales projecting anteriorly. Labial palpus as long as the diameter of eye, drooping, directed downwards. Haustellum short, pale beige. Antennae slightly shorter than forewing; basal part of antennae mostly light brown, distal flagellomeres pure white; scape shorter and thicker than pedicel, dorsally loosely covered with appressed, short, brownish, piliform scales, with 3–5 short, brownish hair-like pecten.

Thorax: Basic color ochreous, with strong metallic gloss. Forewing ground color coppery, with four costal and three dorsal white, black-edged strigulae, and a conspicuous black-lined termen. Strigulae reach near the middle line of the wing. The first costal strigula at 1/3 forewing; the three basal strigulae transversally aligned with the dorsal ones; distal costal strigula on apical fifth. Cilia short, pale brownish at apex and termen, gradually getting longer, and dense, at tornus. Hind wing and cilia blackish fuscous. Forewing venation with 7 veins; Sc ending near 1/3 of costa; terminating apical part with three veins, R 4, R 5, M 1; M 1 and Cu 1 separate; CuP indistinct over entire length; 1A separate; cell closed. Hind wing lanceolate, narrow, venation reduced to four veins: Sc very short terminating near the base of costa; Rs very long, running almost to apex of hindwing; M1 unbranched, ending near 2/3 of dorsum; Cu1 strong, ending slightly before 1/2 of the dorsum. Frenulum – a single stout bristle. Legs slender, general color light brown; hind tibia coppery, with basal and distal margin white; distal tarsomere and pretarsus white.

Abdomen: Dark brownish grey.

Male genitalia ( Figs 2B–E ). Tegumen subconical, longer than valva, slightly rounded apically, with a pair of setae laterally on distal margin; basal parts of tegumen narrow and sclerotized, running parallel to each other with smooth anastomosis into ca. 2/3 part of the tegumen. Tuba analis slightly protruding beyond tegumen. Valvae symmetrical, bar-shaped, with cucullus blunt, curved medially, and bearing fine setae. Vinculum narrow, with short and stout saccus bearing acute distal end. Transtilla narrow for the whole length. Aedeagus tubular, slightly shorter than the valvae, broader basally; vesica tubular, weakly sclerotized, covered by sparse, fine setae, and bearing from one to two slightly sclerotized, hooked shaped cornuti at the apex.

Female adult ( Figs 1C , 2A ). Similar to male in color, but larger in body size. Forewing length: 2.39–2.70 mm (n = 8). Contrary to the male forewing, where the first three costal and dorsal strigulae are transversally aligned, on the female they are outwards, obliquely aligned. Frenulum – 2 tightly appressed bristles.

Female genitalia ( Fig. 2F, G ). Papillae anales lobe-like, semi-rectangular in shape, almost connected dorsally, covered with long, slender setae of greater density on distal section.Anterior apophyses absent. Posterior apophyses long, thickened in ca. basal ¼; apical parts slender, straight and parallel to each other, apices reaching the middle of abdominal segment VII. Ostium bursae opening at the middle of posterior margin of segment VII, followed by short, weakly melanized sterigma. Ductus bursae not separated from the saculiform, membranous corpus bursae. Ductus bursae mostly membranous, except for the slightly sclerotized basal portion. Ductus spermathecae not observed.

Immature stages. Egg ( Figs. 4A–B ; 7D ). Dimensions (mean ± standard deviation; n = 3): length = 0.779 ± 0.010 mm; width = 1.004 ± 0.017 mm. Flat, slightly ellipsoid; chorion translucent ( Fig. 7D ), smooth, ornamented with ill-defined carinae ( Fig. 4B ); vitellum whitish during oviposition, seen by transparency. Aeropyles and micropylar area were not observed.

Larva. Leaf-miner, with hypermetamorphic development and five instars, all endophyllous as found for all lithocolletines. The first three instars are sap feeders, with vestigial thoracic legs, highly modified buccal apparatus, and depressed body; the last two instars have buccal apparatus of chewing type, hypognathous, with the body more cylindrical in shape ( Figs 5A, B ; 7E, F ). Minimum and maximum length of larvae (n = 11) examined for both morphotypes = 0.87 and 4.76 mm, respectively. Within each morphotype, instars can be correctly identified through measurements of the head capsules, since there is no overlap between the head capsule widths of succeeding instars ( Table 1 ). General body color light yellow in all instars.

Sap-feeding larva ( Figs 3A , 4C–M , 7E ). Body covered with sparse microtrichia, particularly around thoracic and abdominal appendices; setae mostly reduced or absent. Head: flattened, prognathous. Labrum bi-lobed, with distally concave, serrated margin ( Fig. 4D, G ). Labium slightly bi-lobed ( Figs. 4E, H ); hypopharynx densely spinose. Maxillary and labial palpi absent. Spinneret is not differentiated ( Fig. 4H ). Antennae tri-segmented, with the distal segment having two globular and one filiform sensillum. Stemmata absent. Four pairs of median-sized setae, laterally, on the middle section of the head ( Fig. 4C ). Thorax: dorsal and ventral plates progressively more developed in later instars ( Fig. 3A ). Legs vestigial, reduced to small callosities ( Figs.4J–K ), each bearing three small setae. Four pairs of setae dorsally on prothorax, two pairs on anterior margin outside the dorsal plate, and two posteriorly located, internal to the plate. Similar setae on meso- and metathorax, the posterior ones located outside the plate, close to its margin. Two pairs of lateral setae with greater size, and unequal length, on each thoracic segment. A pair of dorsal calli on T1-3 next to the lateral margin ( Fig. 4I ). Abdomen: similar to thorax, plates of each segment are progressively more developed in the second and third instars on Ab1-9. Pairs of ventral calli on segments Ab3- 5, each bearing three small setae ( Fig. 4L–M ). Three pairs of dorsal setae, lateral to the plate on Ab1-5; two pairs of dorsal setae, lateral to the plate on Ab 6-9, two pairs of lateral setae, the anterior larger than the posterior one on Ab1-5 and smaller than the posterior one on Ab6-9; one pair of ventral, short setae ( Fig. 3A , 4L ); twelve pairs of setae on Ab10; three pairs dorsally, the anterior ones longer than the posterior; four laterally, the anterior longer than the posterior ones, and five ventral ( Fig. 3A ).

Tissue-feeding larva ( Figs. 3B , 5 , 7F ). Body covered with dense microtrichia. Head subcylindrical, hypognathous. Labrum with concave distal margin, bearing three pairs of setae on lateral margins, and two meso-laterally ( Fig. 5D ). Frontoclypeus ill-defined. Three pairs of ill-defined stemmata, latero-ventrally ( Fig. 5B ). Antennae threesegmented; distal segment narrower, with two stout sensilla, and one filiform sensillum on distal margin; middle segment with four stout sensilla, two of medium size and one short, and one longer, filiform ( Fig. 5F ). Maxillae well developed, with palpi bearing five pairs of stout sensilla ( Fig. 5E ). Spinneret short, tubular ( Fig. 5B ). Chaetotaxy: C1 and F1, present, short; AF1, AF2, P1, P2, and L1, present, minute; A trisetose, short; S trisetose, long; SS trisetose, short ( Figs.5 A-D). Thorax with legs well developed; setae four, two, and four, on coxa, tibia and tarsi, respectively; tarsi with hooked, distal claw ( Fig. 5H ). Prothoracic plate well developed with four rounded lobes ( Fig. 3B ). Prothoracic and abdominal spiracle circular on Ab1-8, with peritreme slightly elevated ( Fig. 5I ). Abdomen with three pairs of pseudopodia on segments Ab3-5 ( Fig. 5J ), and one on Ab10. Crochets uniordinal, distributed on center and anterior margin ( Figs. 5K, L ). Chaetotaxy: thorax with XD group bisetose, with XD2 longer than XD1; SD2 absent on prothorax, but present on meso- and metathorax, and shorter than SD1; D-group bisetose, with D1 shorter than D2. MD1 present on meso- and metathorax. L-group bisetose on prothorax, with L1 shorter than L2; trisetose on meso- and metathorax, near equal in size. SV1 present on all segments, with smaller sizes on meso- and metathorax. V-group unisetose. Abdomen with SD-group bisetose, with SD2 short, located near the spiracle. MD1 near SD2. D-group bisetose, with D1 shorter than D2. L-group bisetose with near equal size on Ab3-5; only L3 present on Ab1-2 and Ab6-8. SV-group trisetose, near to pseudopodia on Ab3-5; only SV1 present on Ab1-2 and Ab6-8. V-group unisetose, present on Ab7 an Ab9. D2, SD1, L3, and SV1 present with near equal size on Ab9. Ten pairs of unnamed setae on Ab10; four pairs located dorsally, one pair laterally and five ventrally ( Figs. 3B ).

Pupa ( Figs. 3C , 6 and 7G ). Yellowish in general color; sub-cylindrical in shape, with head and thorax slightly wider than abdomen, which tapers gradually to posterior apex. Maximum diameter and length of specimens examined (n = 10) = 0.7 and 2.8 mm, respectively. Vertex with relatively short, broadly triangular, acute frontal process (cocoon-cutter) with serrate lateral margins ( Figs. 6 A-D). Lower frons with two pairs of short setae, with lateral setae half the length of mesal ones. Antenna long and straight, extending to 7th abdominal segment (Ab7); forewing reaching almost to Ab6; proboscis extending to middle Ab1; anterior, median, and posterior legs reaching abdominal segments Ab2, Ab4, and Ab7, respectively. One pair of dorsal setae anteriorly located on mesothorax; two pairs of dorsal setae in similar position on metathorax, and Ab1-4 ( Fig. 6F ); one pair of subspiracular setae on Ab4-6. Abdominal segments covered with microtrichia ( Figs. 6G, H ). Spiracle with elevated peritreme, open on Ab2-7 ( Fig. 6G ). Distal margin of the last segment with two pairs of flattened hooks, one dorsal and the other lateral ( Figs. 6 H-I).

Etymology. The specific epithet refers to Arachis L., the food plant, and is treated as a feminine Latin adjective.

Host plant and distribution. Porphyrosela arachisella is known only from cultivated plants of Arachis pintoi Kranov. & W.C. Gregory (Fabaceae) , located in urban gardens of Goiás, Goiás State, and Brasília, Federal District (National Congress of Brazil; Fig. 7A ), from which adults were reared. The hostplant was originally described from the Cerrado, a biome within which such municipalities are located. However, it is unknown whether these plants were locally infested or transplanted with P. arachisella to the urban gardens. Arachis pintoi is an herbaceous, evergreen legume with prostrate growing habitat. It is drought-resistant and well adapted to heavy rain and is cultivated as a forage crop for cattle ( Kerridge & Hardy 1994).

Life history ( Fig.7 ). Porphyrosela arachisella eggs are laid in clusters of three, placed side by side on the upper surface of the leaf, partially overlapping each other on the lateral margins ( Fig. 4A , 7D ). During eclosion, the sap-feeding larvae penetrate the leaf epidermis, leaving the empty chorion on the leaf surface. They promptly initiate the mine, which has a blotch aspect from the beginning, increasing in size during larval development. The sap-feeding larva uses the superficial layer of parenchyma, leaving the transparent, lustrous epidermis intact ( Fig. 7 ). The tissue-feeding stage, however, extends feeding to lower layers, as evidenced by the feeding scars that can be seen by transparency on the abaxial surface on a mature mine ( Fig. 7I ). In the end, it is internally lined with silk by the larvae. In consequence, the leaf is folded upwards, the mine thus showing the tentiform aspect ( Fig. 7H ) typically found among lithocolletine gracillariids ( Kawahara et al. 2017). Pupation occurs inside the mine. During adult emergence, the mine wall is ruptured by the frontal process of the pupa (cocoon-cutter). Generally, after the adult emergence, the anterior half of the pupal exuviae (head and thorax) protrudes outside, while the posterior half remains in the pupal cocoon ( Fig. 7J ).

Frequently, more than one egg cluster is found per leaf. In such cases, mines may coalesce into one, forming larger units that may cover most of the leaf. Porphyrosela arachisella mines are abundant on the Brasília site ( Fig. 7B ), where plants are fertilized and watered periodically. There was no attempt to measure damage they cause to A. pintoi plants, if any.

Figures

FIGURE 1. Adults of Porphyrosela arachisella: (A, C) wings spread, pinned and dried, dorsal view, male (LMCI 344-67, holotype) and female (LMCI 344-69, paratype), respectively; (B) live, with wings folded, on Arachis pintoi leaf surface; (D) distal portion of female forewing in detail, dorsal; (E, F) head in dorsal and lateral views, respectively; (G) hind leg, lateral. Scale bars: 1 mm (A, C), 0.5 mm (B), 0.25 mm (D–G).

FIGURE 2. Porphyrosela arachisella adult morphology: (A) venation of female right wings, dorsal view; (B, C) male genitalia, in ventral and lateral views, respectively; (D) aedeagus, lateral; (E) distal portion of aedeagus in detail (enlarged area delimited by rectangle in D), open red arrow points to cornutus; (F, G) female genitalia under ventral and lateral views, respectively. Closed red arrow and asterisk indicate the posteriorly displaced basal portion of ductus bursae and protruded rectum, provoked by internal hydrostatic pressure. Scale bars: 0.5 mm (A), 0.1 mm (B–C, F–G), 0.05 mm (D–E).

FIGURE 3. Immature stages of Porphyrosela arachisella under light microscopy: (A) sap-feeding larva; (B) tissue-feeding larva; (C) pupa. All in dorsal and ventral view, respectively. Scale bars: 250 μm.

FIGURE 4. Scanning electron micrographs of Porphyrosela arachisella egg (A, B) and sap-feeding larva (C–M): (A) eggcluster, dorsal view; (B) detail of chorion, dorsal; (C–E) head, lateral, dorsal and ventral, respectively; (F) antenna, dorsal; (G) labrum, dorsal; (H) labium, ventral; (I) mesothoracic callus, dorsal; (J) mesothorax, lateral (arrow indicates dorsal callus); (K) vestigial thoracic legs, lateral (indicated by the red rectangle in J); (L) abdominal segment Ab3, lateral; (M) abdominal callus, lateral (indicated by the red rectangle in L). Scale bars: 100 μm (A), 20 μm (B, K, M), 50 μm (C, D, E, J, L), 10 μm (F, G, H, I).

FIGURE 5. Scanning electron micrographs of Porphyrosela arachisella tissue-feeding larva: (A–C) head, in dorsal, ventral and lateral view, respectively (closed and open arrows point to spinneret and stemma, respectively); (D) labrum and frontoclypeus, dorsal; (E) maxila, mesal; (F) left antenna, dorsal, (G) mesothorax, lateral, (H) mesothoracic leg, ventral; (I) prothoracic spiracle, lateral; (J) abdominal segment Ab3, lateral; (K) proleg of abdominal segment Ab5, latero-ventral; (L) crochets in detail, latero-ventral. Scale bars: 50 μm (A, B), 100 μm (C, G, J), 10 μm (D, E, F), 25 μm (H, K), 5 μm (E, I, L).

FIGURE 6. Scanning electron micrographs of Porphyrosela arachisella pupa: (A–B) head, under ventral and lateral views, respectively; (C–D) cocoon-cutter in detail, anterior and ventral views, respectively; (E) abdominal segments Ab1–2, lateral; (F) dorsal setae on abdominal segment Ab1, lateral (area delimited by rectangle in E); (G) spiracle on abdominal segment Ab6, lateral; (H) last abdominal segments, dorsal; (I) corresponding flattened hooks in detail, dorsal (indicated by the red rectangle in H). Scale bars: 100 μm (A, B, E), 25 μm (C), 20 μm (D, F), 10 μm (G), 50 μm (H), 5 μm (I).

FIGURE 7. Natural history of Porphyrosela arachisella at the garden of Federal State Senate, Brasília, DF: (A) general view of the garden; (B) Arachis pintoi plant stand; (C) mines on A. pintoi leaves in detail; (D) eggs on adaxial leaf surface; (E) sapfeeding larva, dorsal; (F) tissue-feeding larva, dorsal; (G) pupa, dorsal; (H, I) mature mines viewed from adaxial and abaxial surfaces, respectively; (J) pupal exuviae protruding from cocoon after adult emergence. Scale bars: 3 cm (C); 100 μm (D), 400 μm (E), 500 μm (F, G, J), 1 cm (H, I).

FIGURE 8. A Neighbor-Joining tree, based on COI barcode fragment generated under the K2P nucleotide substitution model, of Porphyrosela arachisella and its congeners. Each specimen is identified by its Process ID code (see Tab. 2). Branch lengths represent the number of substitutions per site. BIN numbers from BOLD Systems are given on the right bars for all clusters; black bars indicate new BINs. Bootstrap support higher than 50% is presented in the branches.