Peltoschema Reitter

Reid, C. A. M. & Ślipiński, S. A., 2001, Peltoschema Reitter, A Hitherto Unrecognised Chrysomeline: Redescription And Synonymy (Coleoptera: Chrysomelidae), The Coleopterists Bulletin 55 (3), pp. 330-337 : 331-333

Peltoschema Reitter

( Figs. 1–6 )

Peltoschema Reitter 1880:4 . Type species: Peltoschema filicornis Reitter , by monotypy.

Acacicola Lea 1903:392. Type species: Acacicola tristis Lea, by monotypy. New Synonymy

Pyrgo Weise 1901:166 , nec Defrance 1824:273. Type species: not designated by Weise, see below under Pyrgoides Kelly and Reid. New synonymy. Pyrgoides Aslam 1968:129 . This name is a nomen nudum because Aslam failed to designate a type species ( ICZN 1999, Art. 13.3.1).

Pyrgoides Kelly and Reid 1999 [nomen novem for Pyrgo Weise nec Defrance]. Type species: Paropsis hamadryas, Stål , by original designation. New synonymy.

Diagnosis. Adult: head ( Fig. 1 ): median part of frons and clypeus flat, without grooves; head parallel­sided behind eyes, not contracted; posterior margin of clypeus either distinct or effaced, clypeus broadly rectangular if distinct; labrum not densely setose, with 2–5 pairs of discal setae; last segment of maxillary palpi expanded from narrow base to truncate apex, but penultimate segment not grooved to receive apical segment and basal segment without flat carinate expansion of internal margin; apical margin of mentum shallowly concave, not bilobed. Thorax ( Figs. 1–4 ): pronotum glabrous except single large seta in a pit on posterior angles (exceptions noted below); dorsal and ventral anterior margins of prothorax deeply excavate to accommodate head; hypomeron without grooves or excavations; prosternal process flat to evenly curved towards anterior of prosternum, or slightly elevated anteriorly as a narrow triangular ridge; procoxal cavities open, hypomeral lobe short, less than half width of procoxa; elytra glabrous; elytral humeri prominent; epipleuron entirely concealed by produced lateral margin of elytron; median portion of mesosternum visible and mesosternal lobe broad, truncate to slightly concave; tibiae without spurs (Reitter erroneously claimed a spur on each tibia); third tarsal segment not bilobed, apex shallowly concave; claws simple, or basally toothed, or appendiculate. Abdomen ( Figs. 5–6 ): all ventrites free, not fused; apex of ventrite V not depressed or toothed in either sex; ovipositor reduced to pair of one­segmented palpi. All species apparently without secondary sexual modifications of the legs.

2) lateral. Scale bar 5 1mm.

Pupa: the pupa of P. filicornis is unknown, but the morphology of three other species has been described ( Reid 1992); setae not numerous, head and body with typical minimal compliment for Chrysomelini ; abdominal segments lack large setose lateral tubercles; apex of tergite IX unifid or narrowly bifid (urogomphi).

Larva: the larva of P. filicornis is unknown, however larvae of many other species of Peltoschema have been reared by CAMR and these show considerable morphological diversity, especially in the third instar. All larvae are typical of subtribe Paropsina ( Cumpston 1939; Ohno 1958; Reid 1983): Elongate, with a pair of eversible glands between tergites VII and VIII and without pseudopods on the apical sternites. In Peltoschema , body setae are short (not longer than depth of head), the eggbursters are not greatly enlarged and the antennae are not set on prominent angular lobes.

Distribution and Biology. The genus Peltoschema is widespread throughout Australia, and especially abundant in the open woodland and heathland of the south­east, south­west and semi­arid zones. The principle host plant is Acacia s. lat. (which includes about 900 species in Australia; Maslin and Stirton 1997) and several species of Peltoschema may be found on a single species of Acacia at one locality ( Hunt et al. 1996: as Pyrgoides ). Other hosts include various genera of shrubby Fabaceae (pers. obs., CAMR). Many species feed on flowers (but not deliberately on pollen, as claimed by Hawkeswood 1983) of the host, both as adults and larvae ( New 1981; Reid 1992; Hawkeswood 1994), and the predominant colour of both these stages is therefore yellow. However, New (1981) showed that normally flower­feeding larvae could be reared on fresh leaves. Both adults and larvae may be significant pollinators of acacias ( New 1981; Hawkeswood 1983 [note that the record of P. dryope is well outside the known range and is a probable misidentification]). Many acacias only flower in early spring, therefore adults and larvae of Peltoschema are commonly coldseason active. Pupation is in soil.

Notes. The two type species of Peltoschema and Acacicola belong to the same species­group, characterised by the following external adult characters: Anterior of head produced, projecting beyond anterior margin of eyes; junction of frons and clypeus effaced; without groove parallel to inner margin of eye; strong gular ridge between mouth and eye, for retaining antenna; anterior bor­ der of pronotum complete; prosternal process flat anteriorly; 9 regular elytral striae, (excluding scutellar striole), or only stria 8 irregular (semistriate but not forming straight line), with striae 6–7 obliterated at base; lateral margins of elytra evenly curved; epipleuron internal, not laterally visible, glabrous; mesosternal process anteriorly evenly declined, without anterior or lateral ridges for retention of prosternal process; anterior margin of metasternum with simple narrow borders (not triangularly expanded as femoral plates); anterior margin of first ventrite with simple narrow borders (not medially expanded as femoral plates); male first hind tarsal segment without central disc of spatulate setae; claws with small basal lobe, not toothed or appendiculate. Some biological observations have been made of at least 10 species with the above characteristics, and all feed as adults and larvae on acacia flowers. The larvae are undescribed, but late­instars may be distinguished from other species­groups by possessing rows of large posteriorly­directed dorsal tubercles. The filicornis species­group is therefore moderately well­defined physically and biologically. Relatively few species of Peltoschema show all of these attributes.

Many species of Peltoschema are similar to the above, but differ morphologically by one or more of the following: Distinct posterior clypeal margin, anterior margin of pronotum effaced, anterior of prosternal process ridged, lateral margin of elytron swollen, mesosternal process concave, mesosternum strongly anteriorly margined, metasternum with anterior corners expanded into broad triangular femoral plates, anterior margin of ventrite 1 expanded into curved or triangular femoral plates, claws simple or more sharply toothed. None of these variations is considered to be significant at generic level. Apart from these variant species, there are at least three distinct species­groups whose inclusion in Peltoschema may render it non­monophyletic. (1) Includes P. oceanica (Boisduval) , P. quadrizonata (Blackburn) and P. rubiginosa (Chapuis) : Depression or groove beside eye, irregular and obscure elytral striae, setose epipleuron (at least at apex), mesosternal process truncate and strongly transverse. The only known pupa of this group has a bifid urogomphus, unlike typical Peltoschema ( Reid 1992) . (2) Includes P. calomeloides (Lea) and P. daphne (Blackburn) : Depression or groove above eye, elytral striae irregular (semistriate but not forming regular rows), epipleuron horizontal, male hind first tarsus with patch of spatulate setae. (3) Includes a single species, P. nigroconspersa (Clark) : Mesosternal process triangularly swollen, male with pair of circular invaginated pouches on anterior border of ventrites 2–4; host plant in Fabaceae . Several other species currently in Peltoschema have attributes of other genera, for example short spines on tibial apices ( P. orphana (Erichson) , typical of Faex Weise ), or all four corner setae present on pronotum ( P. calliope (Blackburn) , typical of Paropsides Motschulsky ), or all pronotal setae absent ( P. festiva (Chapuis) , typical of Chrysophtharta Weise ). These plesiomorphic or convergent features may not be phylogenetically significant, and Faex and Paropsides may be non­monophyletic, but the precise composition of Peltoschema will require a thorough revision of all the small paropsines, using both adult and immature characters.

Figures

Figs. 1–2. Peltoschema filicornis Reitter (Oodnadatta, South Australia). 1) Dorsal;

Figs. 3–6. Peltoschema filicornis Reitter. 3) Venter of thorax and abdominal ventrite I with coxae removed; 4) male fore tibia and tarsus, latter rotated to show segment shape and planar view of claw; 5) tegmen and penis, dorsal and lateral view, showing outline of flagellum; 6) vaginal palpi and spermatheca.