Cremastobombycia Braun, 1908

Prins, Jurate De & Kawahara, Akito Y., 2012, Systematics, revisionary taxonomy, and biodiversity of Afrotropical Lithocolletinae (Lepidoptera: Gracillariidae), Zootaxa 3594 (1), pp. 1-283 : 158-160

Cremastobombycia Braun, 1908

Cremastobombycia Braun 1908: 272 (key), 349.

Type species: Lithocolletis solidaginis Frey & Boll, 1876 , by subsequent designation by Meyrick 1912b: 11. Cremastobombycia was established to denote a subgenus of Lithocolletis Hübner, 1825 .

Historic account. Based on the stalked M 1 and M 2 in both forewing and hindwing, Braun (1908) erected the subgenus Cremastobombycia after differentiating it from the genus Lithocolletis . Braun (1908) also presented a dichotomous key and added valuable information on the immature stages of Cremastobombycia . She presented five putative characters that diagnose the immature stages of Cremastobombycia : i) larva cylindrical without prolegs on segment X; ii) host plants restricted to the family Asteraceae , iii) mines constructed on the lower (abaxial) surface of the leaf, except C. grindeliella which can mine on both sides; iv) the loosened epidermis of the mature mine very much wrinkled, and v) the cocoon rests suspended inside the mine on silken threads attached at the posterior and anterior ends. Braun (1908) placed five North American species into Cremastobombycia : C. grindeliella ( Walsingham, 1891) , C. solidaginis ( Frey & Boll, 1876) , C. ambrosiella ( Chambers, 1871) , C. ignota ( Frey & Boll, 1873) , and C. verbesinella ( Busck, 1900) . Busck (1909) gave credit to the work of Braun (1908), however, he continued to search for the placement of Cremastobombycia within Lithocolletinae . Busck (1909) concluded that despite the structurally identical characters present in the imaginal stages, each group of Lithocolletinae has retained its typical larval development, feeding habits, peculiar cocoons and its typical forewing coloration. Busck (1909) followed Braun (1908) and postulated the placement of Cremastobombycia in Lithocolletinae . He placed Cremastobombycia Braun and Porphyrosela Braun in equal merit of the classification rank as Phyllonorycter and Cameraria , however not transferring officially these former taxa to the genus rank and clearly recognized only two genera: Phyllonorycter and Cameraria , considering Cremastobombycia as a subgenus of Phyllonorycter . However, he ( Busck 1909: 100) wrote the following: “We have been doing our classification too much horizontally, so to say …. without sufficient regard to its origin. This does not produce a natural system.” However, a year later, probably after reading the argumentation and phylogenetic considerations on the relationship of species groups within Lithocolletinae by Braun (1909), Busck (1910) described a sixth species, Cremastobombycia lantanella , feeding on Lantana sp. (Verbenaceae) from Honolulu, Oahu, Hawaiian Islands and assigned it to the genus Cremastobombycia . In 1902, C. lantanella was intentionally introduced from Mexico into the Hawaiian islands to aid in the control of Lantana sp. ( Busck 1910; Swezey 1910, 1913). No additional species have been added since then. Meyrick (1912b) catalogued Cremastobombycia as a taxon of generic rank and designated the type species Lithocolletis solidaginis Frey & Boll, 1876 . The more specific studies that followed later mainly addressed evolutionary ( Braun 1914; Ely 1918, Davis & Robinson 1998), morphological ( DeGryse 1916; Mosher 1916; Needham et al. 1928), biological ( Swezey & Bryan 1929; Fontes et al. 1994; Palmer & Pullen 1995; Broughton 2000), taxonomic ( Fletcher 1929; Zimmerman 1978; Aarvik et al. 2000), and faunistic aspects of the genus ( Forbes 1923; McDunnough 1939; Brower 1984; Handfield 1997; van Orden Covell 1999; Powell & Opler 2009). The phylogenetic position of Cremastobombycia at the time was unstable, but Braun (1914) was convinced that the genus is of “comparatively recent origin”. Vári (1961), illustrated the type species, C. solidaginis for comparitive purposes, the genus has not been found in Africa until now. According to Vári (1961) Cremastobombycia is related to Protolithocolletis , but differs from the latter genus by the absence of vein R 2 in the forewing. A preliminary phylogeny of Gracillariidae places Cremastobombycia clearly within Lithocolletinae , as the sister genus to Phyllonorycter ( Kawahara et al. 2011) , a result that is corroborated by wing venation ( Braun 1908; Busck 1909).

Cremastobombycia was thought to be distributed only in the New World and C. lantanella to the Neotropical region ( Busck 1910; Palmer & Puller 1995; Baars & Neser 1999). There was no evidence yet that C. lantanella occurs in the Afrotropical region ( Baars & Neser 1999, Urban et al. 2011). We have discovered two native Afrotropical Cremastobombycia species , C. kipepeo De Prins , n. sp. and C. morogorene De Prins , n. sp., and describe both herein.

Diagnosis. We define the genus Cremastobombycia as the assemblage of species-group taxa which fall into the clade Cremastobombycia ( Fig. 4 ). According to wing venation Cremastobombycia is similar to Phyllonorycter Hübner, 1822 ( Braun 1908; Busck 1909), Protolithocolletis Braun, 1929 ( Vári, 1961) and in adult external features to Cameraria : adults are rust-colored moths with silvery-white outwardly margined fasciate and/or strigulate markings on the forewing. Vertex more or less smooth with tufted filiform hairs mainly on occiput, what differs this genus from Cameraria which attain the tufted vertex. Cremastobombycia can be separated from Cameraria and other Lithocolletinae genera in that the forewing M 1 is stalked with M 2, attaining a total of 6 apical veins, much like in Hyloconis and Protolithocolletis whereas forewing of Porphyrosela possess 5 apical veins as in Cameraria and Phyllonorycter . In the hindwing, the median vein is bipartite, forming M 1 and M 2 like in Porphyrosela , Hyloconis , and Protolithocolletis . The interocular suture is thick and strongly sclerotized, arc-shaped (well seen in descaled head). Occular indices of Cremastobombycia similar to Cameraria and Phyllonorycter : the occular index is approximately 0.6 and the interocular index is ca. 1.3. Palpi of Cremastobombycia are similar as in other Lithocolletinae genera: maxillary palpus small, rudimental, bi-segmented, apical maxillary palpomere almost globular, labial palpus moderate, porrect, filiform, drooping, straight, with ratio of segments from base 1: 1.4: 2. Sternum VIII in males forms a characteristic flap laying ventrally under the valvae as in many lithocolletine genera except Chrysaster , Leucanthiza , Macrosaccus , and Protolithocolletis , mostly tapering caudally, with rough lateral edges, setose. Cremastobombycia differs from Cameraria and other Lithocolletinae , except Hyloconis , in the number of apical setae of the tegumen: beside the main pair of long setae, the apex of the tegumen in Crematobombycia has 2–4 additional pairs of shorter apical setae. However, differently from Hyloconis , Cremastobombycia possesses a complete transtilla, a sclerotized anellus, and sometimes a well developed juxta. The valva in Cremastobombycia is stiff, not flexible as in Cameraria , with an enlarged cucullus area covered with short, thick, spinulae-like setae. The female genitalia may be asymmetrical. The ostium bursae in the type species opens at the right side at the posterior margin of segment VII. Segment VIII is short and firmly fused to segment VII. Posterior apophyses with conspicuous triangular appendix at basal 1/3 ( C. solidaginis ). Anterior apophyses arise at the boundary of segment VIII and VII. Ductus bursae strongly melanized along its entire length. The corpus bursae usually is well differetniated from the ductus bursae and usually has one signum. The bulla seminalis may be larger than corpus bursae ( C. solidaginis ). The ductus spermatecae is usually very long, ca. 60 revolutions, loose distally; the bulla spermathecae is sickle-shaped.

Braun (1908) indicated that larvae of Cremastobombycia are cylindrical, without prolegs on segment X. However, diagnostic characters of the larva and pupa beside those indicated by Braun (1908) still need to be carefully examined. Cremastobombycia feeds on Asteraceae ( Braun 1908; De Prins & De Prins 2012), except C. lantanella , which feeds on Verbenaceae . Cremastobombycia larvae construct tentiform mines on the underside of leaf, except C. grindeliella which can sometimes mine both sides of a leaf ( Braun 1908). Pupation occurs inside the mine, inside a suspended, spindle-shaped white silken cocoon, sometimes ornamented with longitudinal ridges ( Braun 1908).

Diagnosis of Afrotropical Cremastobombycia . Afrotropical Cremastobombycia species show differences in wing venation and male genital characters from the Neartic congenerics (see ‘examined additional type specimens used for generic diagnosis’). However, based on the shared similarities of the hindwing venation, forewing pattern, and genital morphology we assign the two Afrotropical species, C. kipepeo and C. morogorene to Cremastobombycia . A third Afrotropical species, belonging to Cremastobombycia , C. lantanella Busck, 1910 was mentioned as a probable invasive pest species to South Africa by Baars & Neser (1999). However, no specimens belonging to this species were detected. Baars & Neser might have confused Cameraria lantanella with the another African gracillariid, Aristaea onychota ( Meyrick, 1908) , which has a very similar wing pattern and also feeds on Lantana . The two Afrotropical Cremastobombycia species are very distinctive in external and internal morphological features.

Head: Vertex not tufted, long piliform scales roughly tufted on occiput, mostly projecting forwards between antennae; frons smooth, shiny white; eyes big. Antenna ca. as long as forewing, smooth scaled, filiform; scape short thickened, bearing pecten of different length. Proboscis developed, naked, of medium length, ca. 2× longer than labial palpus. Maxillary palpus small, rudimentary. Labial palpus moderate, porrect, filiform, drooping, straight.

Thorax: Forewing ground colour ferruginous-ochreous with white and black or only black markings; white markings are margined apically. Descaled forewing lanceolate, slender, and pointed. Afrotropical Cremastobombycia differs from the type species, C. solidaginis , in that forewing is broader and shorter: maximum width/length ratio in C. solidaginis is 0.17, maximum width/length ratio in C. kipepeo is 0.26; and in C. morogorene it is 0.19. Forewing ventation of C. kipepeo and C. morogorene has 8 veins, apical part with 5 veins R 3, R 4, R 5, M 1, Cu 1; M is single, differently from C. solidaginis , where M 1 is stalked with M 2, and apical part in C. solidaginis with 6 veins; the cell between R 4 and R 5 open in C. kipepeo , closed by a very slender rudimentary vein in C. morogorene, Cu 1 separate, CuP indistinct (fold) over entire length, 1A strong, separate. Hindwing lanceolate, maximum width / hind wing length 0.16, venation reduced to 5 veins as in C. solidagini s: Sc very short terminating near base of costa, Rs very long, running nearly to apex of hindwing, M branched to M 1 and M 2, basal 2/3 of M 1 indistinct, parallel to Rs, Cu 1 strong, ends slightly beyond 1/2 of dorsum; A 1 vestigial. Frenulum in male—a single stout bristle, frenula in female—2 tightly appressed bristles, retinaculum—a small fold on Sc. Legs slender, with darker rings; epiphysis on foreleg absent, mesothoracic tibia bears a pair of spurs; hind tibia thickened, with long fine loose hairs, long medial and short apical spurs, hind tarsus smooth, slender and ca. 1.5× longer than tibia.

Abdomen. The anterior boundary of abdomen opening sclerotized; S2 apodemes of median length, ending just before the opening, slender, with broader bases, slender distally. Sternum VIII in adult males well developed, flaplike, extended, tapering caudally, with gently rounded apex.

Male genitalia. Tegumen rather long, with a pair long and many short ( C. kipepeo ) or 5 pairs of equal length ( C. morogorene ) apical setae. Valvae symmetrical, long, straight, with enlarged cucullus area or apical part of valva. Apex of valva is densely setose ( C. kipepeo ) or setose only on ventral and caudal margins of sacculus ( C. morogorene ). Transtilla complete, juxta small. Anellus tubular in C. kipepeo . Vinculum slender and can be apically bipartite ( C. morogorene ). Aedoeagus thick, sclerotized in C. kipepeo and slender with enlarged coecum in C. morogorene ; vesica either with cornuti ( C. morogorene ) or a barb-shaped appendage ( C. kipepeo ).

Female genitalia. Papillae analles flat caudally, fused, with sclerotized outer rim. Segment VIII short, weakly sclerotized. Posterior apophyses without enlarged bases, slender; anterior apophyses initiate at middle of segment VIII, slender, shorter than posterior apophyses. Ostium bursae opens at the posterior margin of segment VII at depth of sclerotized with dentate margin posterior extention of segment VII ( C. kipepeo ). Sterigma very strongly developed and sclerotized, can nearly cover entire sternum VII. Ductus bursae long, rather broad. Corpus bursae oval, mainly as a smooth enlargement of ductus bursae, with one-two signa area, of which one round plate is crossed by sclerotized signum (two short narrow rods, situated opposite each other in C. kipepeo ); corpus bursae with 2 short spikes ( C. kipepeo ).

Biology. No biological data on Afrotropical Cremastobombycia is available. In the Nearctic region, larvae in this genus feed on Asteraceae . They produce a tentiform mine on the underside of the leaf ( Braun 1908; Busck 1910; De Prins & De Prins 2005). Pupation occurs inside the mine, inside a suspended, spindle-shaped, white, silken cocoon ( Braun 1908).

Distribution. Afrotropical Cremastobombycia occur in East Africa, coastal forest and/or savannah.

Relationships to other genera. Cremastobombycia + Phyllonorycter is strongly supported by the eight gene molecular dataset (BP = 100%; PP = 1.0). Although weaker, this clade is sister to Cameraria (BP = 70%; PP = 1.0; Fig. 4 ). See the section on Phyllonorycter for details on shared morphological features.

Figures

FIGURE 4. Molecular phylogeny of Gracillariidae, showing relationships among the Lithocolletinae species sampled for eight nuclear genes in this study. ML bootstrap values are shown above branches, Bayesian posterior probabilities shown below. African taxa are indicated with an asterisk. Scale bar = 0.09 substitutions/site.