Fazia centropogonis (Nishida)
Allograpta centropogonis belongs to a group, Allograpta (Fazia) characterized by: face moderately to greatly produced anteriorly, with distinct tubercle; oral opening about 5 times as long as wide, with oral apex greatly extended beyond level of antennal base; antennal pits separate; plumula well developed; subscutellar pile fringe distinct, one or two rows of long pili; wing broadly bare basomedially, without apical dark macula; alula broad, about 1.5 times as broad as cell BM; metasternum pilose; abdomen broadly to narrowly elongate (Mengual et al. 2009).
Allograpta centropogonis differs from other species in this group by: face with distinct black medial vitta; halter capitulum dark; cell BM completely microtrichose; pleuron black pilose except katepimeron white pilose.
Adults are pollinators and feed on pollen and nectar. Larvae are leaf miners on several Centropogon plant species.
Allograpta centropogonis was described from high elevations (above 2,000 meters) in Costa Rica. Nothing is known about its conservation status but this must be related with the conservation of elevational islands extending south towards and beyond the equator, with the conservation of the Cloud Forests.
Head: Face projecting anteriorly, with distinct but low tubercle, whitish yellow except black medial vitta, shiny, black pilose; gena broad, bare, shiny and yellow on anterior half, brownish, white pollinose and black and white pilose posteriorly; lunule black; frontal triangle yellow except narrowly black along eye margin and dorsad to lunule, dull, black pilose; frons black except yellow arcuate fascia on anterior half, dull, black pilose; male eye contiguity angle about 100 degrees; vertical triangle and vertex black, dull, black pilose; occiput white to yellow on ventral 2/3, black dorsally, white pollinose and pilose on ventral 2/3, silvery pollinose and black pilose dorsally; antenna black, black pilose; basoflagellomere elongate oval, about as long as scape and pedicel together; arista as long as antenna.
Thorax: Bluish black except yellow on notopleuron, postalar callus and scutellum; postpronotum dark brownish black, slightly paler laterally; scutum dull gray to silvery pollinose with darker black medial pollinose vitta, black pilose; scutellum whitish yellow except black laterally and narrowly along margins, sometimes disc darker brownish yellow, dull, black pilose; pleuron silvery pollinose, black pilose except white pilose on katepimeron; spiracular fringes white; plumula large, white; calypter white with black margin and fringe; halter black. Wing: Hyaline except stigma brownish, microtrichose except bare basal 2/3 of 2nd costal cell; vein M1 joining R4+5 perpendicularly; alula normal, microtrichose. Legs: Black pilose; coxae black, silvery pollinose, black pilose; trochanters black, black pilose; pro- and mesofemora brownish orange except black basal third, dull; metafemur black ex-cept brownish orange apical third; pro- and mesotibiae brownish orange; metatibia brownish orange except black apex and with subapical black annulus; tarsi black.
Abdomen: Black with 5 pairs of circular oblique yellow maculae; 1st tergum black except broadly yellow laterally, dull, black pilose; 2nd through 5th terga black except for yellow maculae, dull, black pilose; sterna yellow to orange, mainly black pilose, with some white pile intermixed on 1st to 3rd sterna; male genitalia black, enlarged, with surstyle reddish brown, with surstylar apodeme produced into a medial projecting tubercle between dorsomesial bases of surstyles.
In the field, puparia were not found on the host plants and it was not possible to locate the place of pupation. Under laboratory conditions, the larvae pupated in the plastic bags away from, on or between the leaves. The mature larvae (n = ca. 20) which were placed in fine-mesh bags and left in the field pupated between the bases of leafy liverworts, moss, and lichens. No puparia were found in the soil or leaf litter.
GenBank accession number for this species are: protein-coding COI gene (EF127367), rRNA 28S gene (EF127447) and 18S gene (EU241816).
The subgenus Fazia includes those Allograpta species with the face greatly projected anteriorly. In the previously published key (Fluke 1942), this species would run to either eupeltata Bigot or imitator Curran. Both these species have small male genitalia and eupeltata has a partially pale antenna. Allograpta centropogonis is most closely related to a Chilean species, Allograpta (Fazia) bullaephora.
Larval feeding left conspicuous blotch mines on the leaves. The infested plants were encountered mostly in light gaps and shaded areas. The eggs were laid in clusters on the abaxial side of the relatively mature leaves of the host plants and were usually located near the outer margin between the leaf veins. The number of eggs in clusters ranged from 9 to 72 (mean = 44, S.D. = 17.4, n = 31). About one-third of these clusters had some eggs damaged or detached. Mostly one or two clusters of eggs were observed on a single plant; in a few cases, up to four clusters, but not frequently on the same leaf. No female ovipositional behavior was observed during the investigation. Larval fecal matter was observed inside and outside of mines. Larvae defecated at least twice during their development: while feeding in the last instar and before prepupation.
In comparison with other known syrphine larvae, the larva of A. centropogonis is unusual. All other syrphines of known biology are predators (Rotheray and Gilbert 1999; Rojo et al. 2003), but this species is a leaf-miner. It also has several unique morphological features. These are not unexpected, considering that a shift from a predaceous ancestor has probably occurred.
In the study of Mengual et al. (2008a), the subgenus Fazia was resolved in two different groups. Allograpta centropogonis was resolved in a clade with Allograpta CR-5 and two other new species close to centropogonis, within a bigger clade including Antillus, Costarica, Rhinoprosopa and other species of Fazia. Thompson (in Nishida et al., 2000) suggested that there could be a "clade" of leaf-miners who breed in other Campanulaceae and range from Neotropical Mexico (Chiapas) to Chile based on Allograpta centropogonis, other undescribed species close to centropogonis and two old specimens of Allograpta (Fazia) bullaephora reared, which have a label with the plant name, Lobelia constitucim M. J. RIVERA (Campanulaceae). Mengual et al. (2008a) also hypothesized the existence of a monophyletic subgroup of Fazia of plant-feeders.
The larvae were found mining the leaves of four species of Centropogon: C. costaricae (VATKE) McVAUGH and C. ferrugineus (L. f.) GLEASON at lower elevations (around 2,800 m or below), and C. talamancensis WILBUR and C. valerii STANDL. at higher elevations (3,000-3,100 m). The majority of the mines, eggs, and larvae were found on Centropogon valerii. Plants of C. talamancensis were abundant at the same sites, but only two groups of larvae were mining leaves. In contrast, more than 50 groups were counted on the C. valerii. Under laboratory conditions, C. talamancensis was presented to a group of larvae which were mining the leaves C. valerii under natural conditions and adults were successfully reared. During the investigation (Nishida et al., 2000), more than 15 cohorts of the Allograpta centropogonis were reared. However, no parasitoids were obtained, and no parasitoids attacking the eggs or larvae were observed. The only natural enemy found was a larva of an unknown syrphid species which was preying on the eggs of the Allograpta centropogonis. Rearing of this predatory syrphid was thwarted by vandalism in the field. Along with the larvae of A. centropogonis, individuals of a species of Ortheziidae (Homoptera) were frequently found on the abaxial surface of leaves of Centropogon spp.; however, no predatory behavior toward the homopteran was observed. Some adult males visiting flowers of enecio oerstedianusS BENTH. and Ageratina ixiocladon (BENTH.) R.M. KING & H. ROB. (Asteraceae) were seen around 10:30-11: 30 A.M. when the sun was shining strongly.
The eggs and larvae were observed more frequently in May through September than in April or October. In the laboratory, eggs collected on the 8th of April hatched on the 10th of the same month. Pupation took place on the 26th to 28th of the same month (the larval stage lasted 17 to 19 days including the prepupal stage). Adults emerged on the 15th to 16th of May (the pupal stage lasted approximately 21 days). In the field (Estacion Biologica Cerro de la Muerte, March to July, 2001), the egg stage took more than two weeks, the larval stage about a month, and the pupal stage lasted close to two months.
Allograpta centropogonis was found in the high elevations (2,000 m and above) in the mountains of the Talamanca region and Volcan Barva in Costa Rica. Adults were found in most months (no records for February and March), with the peak being from September to January. See GBIF: http://data.gbif.org/species/13356657/
The forest in the regions where it was collected is described as a Tropical Montane Rain Forest or as a Tropical Montane Cloud Forest.
Egg. ca. 1 mm long, white, elongate, oval-cylindrical.
Description of the third stage larva and puparium Overall appearance: A subcyclindrical green larva with a white fat body covering the hind gut; tapering anteriorly, truncate posteriorly; locomotory organs with shallow grooves, lack¬ing prolegs and crochets; papillae bearing antenno-maxillary organs flattened laterally and surrounding the mouth; apex of head skeleton with serrated dorsal and ventral margins; posterior respiratory process short, broader than long with a non-sclerotised, fleshy base and three pairs of radially arranged spiracular openings extending down the sides of the dark brown apex.
Third stage larva: Length 9-11 mm; width 1.5-2 mm; subcyclindrical in cross section, tapering anteriorly, truncate posteriorly (Fig. 4). Dorsal and ventral sensilla accompanied by single setae, sensilla on pro thorax, ventral surface and anal segment lacking setae. Pattern of segmental sensilla as for other syrphid larvae (ROTHERAY & GILBERT 1999). Head: Antennomaxillary organs mounted on large, laterally flattened papillae (basal width 0.17 mm) that cover the sides of the mouth. Head skeleton: Arrangement similar to other syrphines (HARTLEY 1963, ROBERTS 1970), i.e. labrum and labium elongate and equally produced at the tip of the head skeleton. The tips of the labrum and labium not sharply pointed as in other syrphines. Instead the dorsal surface of the labrum bears two rows of 4-5 hooks. These rows taper and the hooks become larger toward the apex of the labrum. The ventral surface of the labium bears similar rows of hooks so that, in the lateral view, the tip of the head skeleton appears serrated. Mandibles apparently reduced or lost. Dorsal cornu narrow and spike-shaped. Thorax: Dorsal and ventral margins of prothorax above and below the mouth with a fleshy lobe (width 0.08 mm). Lateral margins of the thorax and the first abdominal segment coated with sclerotised vestiture, this vestiture extending onto dorsal surface on anterior margins of transverse folds. Elsewhere surface of integument matt. Anterior spiracles present on posterior fold of prothorax. Ventral surface of mesothorax with a pair of raised pads. Abdomen: Abdominal segments 1-7 with four transverse dorsal folds. Surface of integument matt, lacking sclerotised spicules. Paired locomotory prominences on abdominal segments 1-7 bearing sensilla 9 and 10 with apex matt bearing shallow grooves. Anal segment: about equally developed dorsally and ventrally with two dorsal and three ventral folds. Not as high as abdominal segment seven (height at mid-point: anal segment 1.28 mm versus abdominal segment seven 2 mm) and truncate at apex. Apex bearing a pair of lobes (0.34 mm wide by 0.28 mm long) and a pair of smaller more lateral lobes (0.2 mm wide by 0.17 mm long). Anal opening transverse. Posterior respiratory process: length 0.25 mm; basal width 0.57 mm; base fleshy, not sclerotised, upper half bearing spiracular plates sclerotised and nodulate. Spiracular plates with three pairs of spiracular openings extending over the sides of the sclerotised apex. Four pairs of interspiracular nodules bearing setae present, often individual setae lacking. Puparium: Length 5-6 mm; dark brown dorsally; anterior segments with green transverse bands; creamy white color "zigzag" stripe laterally; pale brown to brown ventrally; dorsal surface inflated and arched dorsally. Anal segment small and narrow compared with rest of puparium. Pupal respiratory process absent.
The first instar larvae, after hatching from the eggs, fed gregariously on the leaf tissue adjacent to where they hatched, toward the central vein of the leaf. In the field, recently hatched first instar larvae were encountered between the hours of 12:00 p.m. and 1 :00 p.m (n = 2). At this position, the larvae did not mine the leaf; instead, they fed on the tissue from the outside by puncturing the leaf epidermis and mesophyll. This feeding behavior left relatively small (approximately 6 mm X 4 mm) white blotches on mature leaves; these white blotches were easily seen in the field. After feeding on this part of the plant, it appears that the larvae crawled up to the plant apex and fed on folded young leaves, then young unfolded leaves, again without mining; some larvae were between the leaf folds. Feeding by larvae at the apex caused secretion of plant latex which coagulated and adhered to the surface, and was also observed on some flower buds and fruits located at the tip of the plants. Later, the larvae were observed gregariously mining, lined up side by side ("shoulder to shoulder"), in a young unfolded leaf near the apex, and later in a mature leaf located lower down. This feeding pattern, and the switching of feeding positions, was observed on all infested plants (n = ca. 50); however, it was not possible to document the migration of the larvae from one feeding position to the next in the field. Under laboratory conditions, the first instar larvae migrated gregariously in a single line, one behind the other, crawling along on the central vein near lamina of the plant (n = 1). To begin mining, the larvae scrape through the epidermis with their mouth hooks, making one to a few holes on the abaxial surface of the leaves. Evidently this entrance hole can also serve as the exit hole; some of the empty mines presented only one hole. The larvae twisted the head and placed the mouth parts side-ways, using the labium and labrum like scissors (opening and closing) for food intake. When the head is twisted to the right, the larva feeds toward the left, and when the head is twisted to the left, the larva feeds toward the right. A first instar larva opened and closed the labium 100 times in 48 seconds (2.08 times/second), giving three head turns of 0.5 mm right to left. The feeding distance advanced about 1.5 mm toward the apex in 20 minutes. A third instar larva opened and closed the labium 100 times in 46 seconds (2.17 times/second), giving three head turns of 3 to 4 mm right to left (or left to right). Both cases were observed under laboratory conditions (temperature: 23-24 °C). First instar larvae molted in the mines; molts and head skeletons were found inside the mines. The second instar larvae molted in and outside of the mine. Presumably the larvae were gregarious until the last part of the second instar. The molting took from the posterior to the anterior of the body. The third (last) instar larva was usually mining alone or in small groups of two or three individuals per mine, scattered on several mature leaves. Several recently molted third instars were resting outside of the mine and later started to mine the leaf. The larvae commenced the mine near the tip of a mature leaf and mined in the direction of the base of the leaf. In most cases, the leaf-mining larvae switched leaves before consuming an entire leaf. In several cases, the second and third instar larvae were found resting on the surface ofleaves or in mines without mining. A mature larva outside of the leaf moved about 60 mm in 30 seconds in a straight line on the flat surface of a leaf (n = 1, air temp. = 15 °C).
Adult syrphids are crucial pollinators of flowers and the immatures recycle nutrients. Subfamily Syrphinae was previously assumed to contain only species whose larvae are predators on various insects and mites. The biology of Allograpta centropogonis changes this vision and may have important implications, such as agricultural quarantines and exportations with syrphine larvae.