Porphyrosela Braun 1908

Porphyrosela Braun, 1908

Porphyrosela Braun 1908: 272 (key), 348.

Type species: Lithocolletis desmodiella Clemens, 1859, by monotypy. Porphyrosela was established to denote a subgenus of Lithocolletis Hübner, 1825.

Historic account. Braun (1908) established Porphyrosela as a subgenus of Phyllonorycter based on four characters: i) forewing somewhat acuminate; ii) absence of vein R 3 in forewing; iii) scape of antenna without pecten; iv) hind tibia without appressed hairs. In the same publication Braun assigned Lithocolletis desmodiella Clemens, 1859 to Porphyrosela, which remains the only Nearctic species belonging to this genus. Busck (1909) confirmed the subgeneric status of Porphyrosela and considered it closely related to Cremastobombycia and Phyllonorycter. These three taxa showed a “cylindrical” type of larvae, common to many present-day Lithocolletinae and according to Busck (1909: 100) “are worthy of subgeneric rank...but to erect subgenera for two of the subdivisions [Porphyrosela and Cremastobombycia, note JDP] of the one main branch and then include the other main branch [Cameraria, note JDP] in the third subdivision [Phyllonorycter, note JDP] is obviously unscientific”.Therefore, Busck (1909) only recogized two genera, 1) Phyllonorycter Hübner (including species currently in Porphyrosela, Phyllonorycter and Cremastobombycia) and 2) Cameraria Chapman. Braun (1909) followed his division of lithocolletine species into two main branches “cylindrical larva” and “flat larva”, regarded the Porphyrosela group closely related to the Phyllonorycter group, but differently from Busck (1909) placed Cremastobombycia at the base of both branches. Subsequently, Braun (1914: 150) combined her larval morphological data with wing pattern data of Lithocolletinae, and concluded that Porphyrosela is derived from Phyllonorycter, but “ Cremastobombycia (in its modern form) and the “flat-larval group”[Cameraria, note JDP] originated at a somewhat later period than the typical Lithocolletis [Phyllonorycter, note JDP]”. The taxonomic status of Porphyrosela remained an item for discussions for microlepidopterists. Differently from Cremastobombycia, which was treated at generic level by Meyrick (1912b), desmodiella was treated by Meyrick in the same publication as a species of the group C of Lithocolletis. But DeGryse (1916), in a publication on larval hypermetamorphism, recognized Porhyrosela as a separate genus. Ely (1918) also treated Porphyrosela as a separate genus based on wing venation and listed the same diagnostic characters which were presented in the original description of Braun (1908), which was followed by most subsequent workers (e.g., McDunnough 1939; Bourquin 1951; Clarke 1953). However, Fletcher (1929) still considered Porphyrosela as a subgenus of Lithocolletis. Vári (1961), in his seminal treatment of Afrotropical Lithocolletidae added and corrected the diagnostic characters of Porphyrosela because some of the characters were erroneous. For instance, he noted that the scape of Porphyrosela has a pecten with a few hairs, that four apical veins are most probably present in the forewing, that the hindwing is narrower than in Phyllonorycter, and that Rs and M 1 are coincident at their base and very weakly sclerotized. Furthermore, Vári (1961) noted the simple diagnostic difference between Porphyrosela and Phyllonorycter, that the anterior apophyses are absent in Porphyrosela, but present in Phyllonorycter. Vári (1961, 1963) added the descriptions of two Afrotropical Porphyrosela species to the two species then recognized in the genus. Kumata (1993) confirmed and broadened the definition of Porphyrosela by noting that Porphyrosela in Asia have a hairy pecten on the scape, tufted upperside of hind tibia, and veins R 3, R 4 and R 5 in the forewing. Kumata (1993) also noted that veins in the hindwing are very weakly sclerotized, and that three pairs of sensillae represent the veins Cu 1, M 1 and M 2 which might serve as a diagnostic character separating it from Phyllonorycter. Kumata (1993) added another diagnostic character found in the male genitalia: the tegumen of Porphyrosela has a pair of apical setae, which easily separates this genus from Phyllonorycter, which lacks apical setae. Kumata transferred aglaozona Meyrick, 1882, dismochrysa Lower, 1897 [misspelled as desmochrysa, note JDP], dorinda Meyrick, 1912, neodoxa Meyrick, 1916 and hardenbergiella Wise, 1957 from Phyllonorycter to Porphyrosela, described alternata Kumata, 1993, augmenting the list of Porphyrosela species to ten. Publications that followed mainly catalogued the known Porphyrosela species and contained additional biological and distribution data (Biezanko et al. 1978; Inoue et al. 1982; Brower 1984; Grehan et al. 1995; Covell 1999; Sugi 2000; Dall’Asta et al. 2001, Vári et al. 2002; De Prins & De Prins 2005; Bai et al. 2009), or data on parasitic Hymenoptera attacking Porphyrosela (Yoshimoto 1977; Maier 1988; Kamijo 1991). Kumata (1993, 1995) provided a much detailed redescription of Porphyrosela dorinda (Meyrick, 1912). The preimaginal stages of the genus, based on the detail examination of larval and pupal characters of Porphyrosela minuta Clarke, 1953 were studied by Bentancourt & Scatoni (2007).

Porphyrosela occurs in all biogeographical regions except Antarctica, although the genus included only 10 species (De Prins & De Prins 2012). In the Palaearctic region, there are two recognized species (P. alternata Kumata, 1993 and P. dorinda (Meyrick, 1912)), in the Nearctic region there is one (P. desmodiella Clemens, 1859), in the Neotropical region there are two (P. desmodiella Clemens, 1859 and P. minuta Clarke, 1953), in the Oriental region there are three (P. alternata Kumata, 1993, P. dorinda (Meyrick, 1912) and P. neodoxa (Meyrick, 1916)), and in the Australian region there are three (P. aglaozona (Meyrick, 1882), P. dismochrysa (Lower, 1897), and P. hardenbergiella (Wise, 1957). The Afrotropical region was represented by two Porphyrosela species: P. homotropha Vári, 1963 and P. teramni Vári, 1961. Herebelow, we present two more Afrotropical Porphyrosela species augmenting the number of Porphyrosela species in the Afrotropical region to four.

Diagnosis. The genus Porphyrosela contains some of the smallest moths in Lepidoptera (Kumata, 1993), with ca. 4.5–4.7 mm wingspan. Porphyrosela superficially resembles Phyllonorycter by wing pattern and venation. The ground forewing colour of many Porphyrosela species is orange ferruginous with metallic highlights marked with broad white rounded or strigulate spots surrounded by a narrow black border. Veins are weakly developed. The forewing can contain 4 or 5 apical veins, depending whether R 3 and R 4 are rudimentary or developed. In hindwing, Rs is very long like in Phyllonorycter and M 1 can be branched just beyond the middle and extend almost to subtornum M 1 and defined M 2 (Kumata 1993). The presence of M 1 and M 2 on hindwing might assist in separating Porphyrosela from similar Phyllonorycter species (Kumata 1993). M 2 is also present in Protolithocolletis and Cremastobombycia, but these genera possess six (in Cremastobombycia, except the Afrotropical taxa) or seven (Protolithocolletis) apical forewing veins. Afrotropical Cremastobombycia differs from Porphyrosela by having more than 2 pairs of apical setae on tegumen in male genitalia and the origin of apophyses anteriores at segment VIII in female genitalia. Porphyrosela also differs from Phyllonorycter by possessing a pair of apical setae on tegumen in male genitalia; in Phyllonorycter such setae are lacking from the apex of the tegumen (Kumata 1993). The female genitalia of Porphyrosela differ from those of Phyllonorycter and other Lithocolletinae by having a reduced eighth abdominal segment without anterior apophyses (Vári 1961; Kumata 1993). Anterior apophyses that extend from segment VIII in female genitalia are absent in the Phyllonorycter melanosparta group. However, in the latter species group the sterigmatic appendages located in segment VII are probably homologous with the anterior apophyses. The larva has been studied in only one species, P. minuta Clarke, 1953, by Bentancourt & Scatoni (2007). Porphyrosela species possess three flat, legless, sap feeding, early instars and two cylindrical, tissue feeding, later instars with developed legs, prolegs and chewing mouthparts. Chaetotaxy of the last fifth instar of Porphyrosela is unique within the Lithocolletinae, seta SD2 from the prothorax and the SV group on three thoracic segments are absent (Bentacourt & Scatoni 2007). In most of other gracillariid genera, the SV group is present on thoracic segments (Davis 1987). The pupa of Porphyrosela is slender and subcylindrical with a well developed cephalic process. Apices of the antennae and metathoracic legs coincide at the same length (Bentancourt & Scatoni 2007), whereas in Phyllonorycter the antennal appendages are shorter than the thoracic legs and in Cameraria the antennal appendages are longer than the thoracic legs (De Prins et al. 2003). The abdominal segments of Porphyrosela pupa have abundant spinulas and rounded spiracles, whereas the other pattern is present also in the remaining Lithocolletinae genera (De Prins et al. 2003; Bentancourt & Scatoni 2007). The cremaster is reduced (Betancourt & Scatoni 2007), whereas in Phyllonorycter it is present and in Cameraria it is absent (De Prins et al. 2003). Larvae of Porphyrosela feed primarily on Fabaceae (De Prins & De Prins 2005; 2011), and the majority of species build underside mines, but P. minuta constructs an upperside blotch mine. Unlike most other Lithocolletinae genera, Porphyrosela is usually gregarious with two or more larvae (up to six) in each mine (Vári 1961; Maier & Davis 1989; Wessels 2010). The duration of larval development, for P. minuta, lasts 8–9 days (Bourquin 1951; Bentancourt & Scatoni 2007). Pupation takes place inside the mine in a chamber on the epidermis of leaf that is constructed by the larva at the end of its development (Bourquin 1951). The pupa remains free inside the mine and does not make a cocoon; the exuvium is partially exposed after the adult emerges. For P. minuta, pupation lasts only 4–5 days (Bentancourt & Scatoni 2007).

Diagnosis of Afrotropical Porphyrosela . Interspecific differences of Porphyrosela are most readily detectable based on wing pattern. Afrotropical Porphyrosela show no differences in wing venation from the Palaearctic species P. dorinda and P. alternata (Kumata 1993: pl. V, figs C & D). Male and female genitalia of the Afrotropical species show only very minor differences providing insufficient diagnostic characters for species identification.

Head: Vertex plate tightly joint with frontoclypeus, vertex and occiput tufted with erected fuscous-ochreous long piliform scales; frons covered with appressed smooth scales, with strong metallic gloss; eyes medium sized, slightly smaller than eyes of Phyllonorycter, ocular index ca. 0.5, interocular index ca. 0.7. Antenna ca. as long as forewing, smooth scaled, apical flegellomeres might be pure white (P. teramni) filiform; scape short thickened, bearing a few hair-like pecten or without pecten. Proboscis developed, naked, slightly shorter than proboscis in Phyllonorycter, ca. 2.3× longer than labial palpus. Maxillary palpus small, rudimental, bi-segmented, apical maxillary palpomere almost globular. Labial palpus moderate, porrect, filiform, drooping, with ratio of segments from base 1.1: 1: 1.3.

Thorax: Forewing background colour ochreous with silvery white markings; fringe long, particularly near tornus and dorsum, reaching width of wing in forewing and ca. 4–5× width of wing in hindwing. Descaled forewing lanceolate, slender, and pointed. Venation with 8 veins, apical part with weak 5 veins R 3, R 4, R 5, M 1, Cu 1; M 1 and Cu 1 separate, CuP indistinct (fold) over entire length, 1A separate; Sc strong and short. Veins R3 and R4 might be rudimentary, very slender and indistinct; cell closed. Hindwing lanceolate, narrow, maximum width/hind wing length is 0.1, venation reduced to 5 veins: Sc very short terminating near base of costa, Rs very long, running almost to apex of hindwing, M 1 double branched to M 1 and M 2, both branches running close and almost parallel to each other, basal 2/3 of M 1 indistinct, parallel to Rs, distal parts of M 1 and M 2 run along dorsal margin, Cu 1 strong, ends slightly before 1/2 of dorsum; A 1 vestigial. Frenulum in male—a single stout bristle, frenula in female—2 tightly appressed bristles. Retinaculum in male a tiny fold on Sc. Legs slender, without rings; hind tibia thickened with a few aprressed hairs, with long medial spurs slightly longer tha apical spurs, hind tarsus smooth with darker and brighter shading but not evidently ringed, slender, ca. 0.6× length of tibia.

Abdomen. Anterior margin of abdomen opening narrowly sclerotized and significantly broader towards S 2, the sclerotized margination of abdomen opening well connected on T 2 and unconnected on S 2; S 2 apodemes of rather long, ending beyond the opening, slender, bent in midden, with slightly enlarged bases, slender distally, a pair of tiny spicules present on each abdominal sternum sublatero-anteriorly. Sternum VIII in adult males small, flap-like, extended, more or less rounded caudally.

Male genitalia. Tegumen rather long, conical or subconical, blunt apically with a pair of apical or subapical setae; tuba analis slightly protruding or indistinct. Valvae symmetrical, about as long as tegumen, slender, barshaped, weakly arched at subapex, round apically with fine scattered setae. Transtilla is complete, narrow. Anellus well developed, tubular, without sclerotized juxta. Vinculum narrow, with short or medium length saccus. Aedoeagus nearly as long as valva, tubular, tapering beyond middle towards apex, one side of vesica heavily but narrowly sclerotized (P. teramni) or bearing cornutus (P. gautengi).

Female genitalia. Papillae analles short, narrowed dorsally and ventrally; posterior apophyses long, running to middle or beyond middle of segment VII, straight, slender basal region can be slightly widened in P. homotropha. Segment VIII reduced, shortened; anterior apophyses absent. Ostium bursae opens near caudal margin of segment VII; sterigma absent. Ductus bursae is weakly scerotized, without antrum; corpus bursae not distinct, without signum.

Relationships to other genera. The phylogenetic position of Porphyrosela remains unclear, as species in this genus have not been sequenced. Species in Porphyrosela are rather uniform morphologically both externally and internally, suggesting that the genus may be a monophyletic assemblage of similar species. Most diagnostic characters are found in the forewing pattern, such as the number and shape of patches and strigulae. The genitalia do not show evident and significant interspecific differences. Valvae of Porphyrosela are rod-like, sparsely setose with rounded or slightly obtusely angulated apex, vinculum in males more or less subriangular or slightly different shape with short sacccus. The differences are even less conspicuous in female genitalia, such as minute differences in the shape and length of posterior apophyses. Most Porphyrosela species are oligophagous and feed on closely related host plants.

Biology. The mine is oblong, transparent, and tentiform, on the underside (abaxial) leaf surface (P. teramni) or it is constructed on the upperside (adaxial) of the leaf (P. homotropha); mine strongly contracted; no folds (P. teramni) or several folds (P. homotropha) visible; larvae gregarious in mine (P. homotropha, P. teramni); frass in one or two clusters; pupation without cocoon; pupa protrudes the mine before adult emerges (Vári 1961). Afrotropical species, like all other Porphyrosela species, feed on Fabaceae.

Distribution. Afrotropical Porphyrosela occurs in Cameroon, Ethiopia, South Africa and Zimbabwe.