F O L I A E N T O M O L O G I C A H U N G A R I C A R O V A R T A N I K Ö Z L E M É N Y E K

L U (1991) 1992 p. 29-34

Taxonomic notes on Cyphogastra Deyrolle (Coleoptera: Buprestidae), II. The Suturalis-circle

By

R Holynski

(Received July 15, 1988)

Taxonomic notes on Cyphogastra Deyrolle (Coleoptera: Buprestidae) II. The Suturalis-circle. - The term "circle" is proposed to denote delimited group of closely related species within a subgenus. The Suturalis-circle of Cyphogastra Deyrolle is reviewed, a key is presented and the phylogenetical history reconstructed.

After having reviewed (Holynski 1992) the subgenus Guamia Théry, I found myself face to face with a virtually incomprehensible jungle of forms, localities and names be­longing - or, at least, attributed - to the nominate subgenus. Fortunately, as is usually the case with species in large genera, this swarm is divisible into more or less clearly definiable sections, which can be analysed one by one. The use of such a category, inter­mediate between species and subgenus, is frequently very convenient in taxonomical dis­cussions, and indeed many zoologists have recourse to it. Yet some confusion comes from the surprising fact, that apperantly no appropriate technical term is available, supraspe-cific subdivisions of subgenus being usually referred to as either (incorrectly) superspe-cies or (imprecisely) group. In this situation I found it necessary to introduce the term "circle", defining it as follows: a circle is a group of closely related species, nomenclatu-rally informal, but otherwise having all the properties of an infrasubgeneric taxon. As such, circles must be in particular:

monophyletic (but not necessarily holophyletic), i . e. all the ancestors of any member of a circle, back to - and inclusive of - the common ancestor, belonged to that circle;

exhaustive, i . e. each species of a subgenus belongs to one circle or another; exclusive, i . e. a species belonging to one circle does not belong to any other; equivalent, i . e. accepted minimum of difference between - and accepted maximum of

variation within - circles should be approximately equal. So defined, the category of circle, a little informal as it is, fits nevertheless very well

into the system of hierarchical evolutionary classification. The Suturalis - circle is characterized by relatively flat body not or very indistinctly

caudate elytra; evenly convex (with no trace of differently sculptured longitudinal sulci) elytral surface; bluish suture (or all the elytra bluish-black to black); protibia with a sharp keel along the external ridge, bordered on both sides by deep furrows; pronotal grooves irregular and/or lateroposterior elevated relief triangular. None of these features is diag­nostic by itself, but together they make the circle a well-defined group and strongly sup­port its monophyly (in evolutionary, not cladistic, sense, i . e. monophyletic group must contain all surviving or extinct progenitors of the species included, down to at least their last common ancestor, but not necessarily all the descendants of the latter).

The synonymy in this group is rather complicated. I have identified 16 published names as belonging to various forms of the Suturalis - circle, but the number of really distinct taxa is obviously much less. After excluding the geographically remote, New Hebridean C. tuberculata Thomson (well defined by its big size, extremely prominent abdominal pla­que, unique-black above, purplish underneath - colouration etc.) and the distinctively bi-colorous Buruan C. nigripennis Deyrolle, we find ourselves with bewildering conglome­rate of forms, known under variety of names according mainly to colouration and elytral sculpture. Usually C. suturalis (Fabricius), C. ignicauda Deyrolle, C. punctipennis Dey­rolle, C. aereipennis Kirsch, C. cupriventris Kerremans, and C. carbonaria Théry are considered distinct species, but Théry (1926) includes the last one as a variety into C. punctipennis Deyrolle, grouping all the others (nay C. nigripennis Deyrolle!) under C. su­turalis (Fabricius).

My study has shown, that the colouration of the dorsal surface and the coarseness of elytral puncures vary individually without apparent correlation among themselves, with other features or with geography. There are, however, two sets of concordantly variable characters in the forms with green-to-coppery ventral side: in specimens from Halmahera and surrounding islands (Morotai, Ternate, Batjan, Kaioa) proepisterna are covered by uniform, fine and dense punctulation, pronotal grooves show more or less distinct flat, densely and finely punctured bottom surfaces, and the tarsal colouration is brown or black without apparent metallic shine, while in those from the Southern Moluques (Obi, Ceram, Amboina etc.) there are distinct smooth reliefs on proepisterna, densely puncut-red surfaces within pronotal grooves are not developed, and tarsi are decidedly golden or green. The differences are not absolutely consistent, so I regard them as subspecific, the race from Ceram, Amboina, Saparua and Obi representing C. suturalis (Fabricius) s.str., while the northern form should be referred to as C. s. ignicauda Deyrolle.

The specimens with bluish-black undersurface - known to me from Halmahera, Ter­nate, and Amboina - do not conform to the pattern described above, having always evenly, densely punctured proepisterna, relatively big areas of similar sculpture in pro­notal grooves, and non-metallic tarsi. They evidently represent a separate species especi­ally (closely related to C. s. ignicauda Deyrolle). It is usually found in collections under the name "C. punctipennis Deyrolle, var. C", but judging from the description (Deyrolle 1864), C. punctipennis Deyrolle itself is a variety of C. suturalis ignicauda Deyrolle. I have not seen the type of C. carbonaria Théry, but very probably this is the proper name for all-black Moluccan species.

Two syntypes of C. cupriventris Kerremans in the British Museum, as well as speci­mens determined by Kerremans as C. punctipennis Deyrolle and C. cyaneomicans Ker­remans, belong to C. suturalis ignicauda Deyrolle, whereas the syntype of C.obscura Kerremans and two syntypes of C. aeneicollis Kerremans represent the nominative subs­pecies. The original description of C. ludekingi Obenberger and C. ludekingi halmaheirae Obenberger (Obenberger 1922) leave little doubt that they belong to the same species: probably the former is a bluish-black variety of the southern, and the latter - that of the northern race. Similarly, C. tevorensis Obenberger seems to represent a variety of C. su­turalis (Fabricius) s.str. (I have been unable to locate Tevor on any map - may be it is Tioor, the southeastern island of the Ceram group?), while C. aereipennis Kirsch and C. azurea Kerremans belong to C. s. ignicauda Deyrolle. As to C. satrapa (Schönherr), I take it as the synonym of C. suturalis (Fabricius) s. str. after Obenberger (1926).

The following synonymy appears from the foregoing discussion: Cyphogastra suturalis (Fabricius, 1801), Syst. FJeuth. 2:195 (Buprestis) =satrapa (Schönherr, 1817), Syst. Ins. 1, 3:251 (Buprestis) =aeneicollis Kerremans, 1895, Ann. Soc.Ent.Belg. 39:201 =obscura Kerremans, 1895, Ann.Soc.Ent.Belg. 39:202

=tevorensis Obenberger, 1922, Arch.Natg. 88(A):66 =ludekingi Obenberger, 1922, Arch.Natg. 88(A):66 ssp. ignicauda Deyrolle, 1864, Ann.Soc.Ent.Belg. 8:42 =punctipennis Deyrolle, 1864, Ann.Soc.Ent.Belg. 8:44 =aereipennis Kirsch, 1885, BerLEnt.Zschr. 29:113 = cupriventris Kerremans, 1895, Ann.Soc.Ent.Belg. 39:200 = cyaneomicans Kerremans, 1903, GenJns. 12:87 = azurea Kerremans, 1910, Mon.Bupr.4, 6:191 =halmaheirae Obenberger, 1922, Arch.Natg. 88(A):67 Cyphogestra nigripennis Deyrolle, 1864, Ann.Soc.Ent.Belg. 8:43 Cyphogastra tuberculata Thomson, 1878, Typi Bupr.:22 Cyphogastra carbonaria Théry, 1908, Ann.Soc.Ent.Belg. 52:81

Key to the identification of species of the "Suturalis-circle"

A(B) Elytra strongly caudate; or elytra with longitudinal sulciform depressions in pos­terior half; or pronotal lateroposterior depression with broad, contiguous, finely and densely punctulated bottom surface; or elytra green with concolorous suture; or prono­tum contrastly darker than elytra other groups of Cyphogastra Deyrolle s.str. B(A) Elytra not or only slightly caudate; elytra withouth depressions behind mid-length; lateroposterior depressions of pronotum without distinctively punctured bottom surfa­ces, or these are small, divided into anterolateral and posterior parts by coarsely punc­tured elevation; elytra black or suture bluish; pronotum not darker then elytra

Suturalis-circle 1(2) Abdominal plaque acute-angled in profile, its height equal to distance from hind margin of second sternite, ventral line concave C. tuberculata Thomson 2(1) Abdominal plaque obtuse-angled or its height less than distance from posterior margin of 2nd sternite; ventral line straight or convex in profile 3(6) Dorsal surface (except elytral tips) nearly unicolorous or elytra green 4(5) Ventral side blackish C. carbonaria Théry 5(4) Ventral side green or coppery (C. suturalis Fabricius) 5a(5b) Proepisterna with smooth, elevated reliefs; pronotal depressions without distinc­tively punctured surfaces; tarsi brightly metallic C. suturalis suturalis (Fabricius) 5b(5a) Proepisterna uniformly, densely and finely punctulated; densely and finely punc­tured bottom surfaces in pronotal foveae well developed; tarsi blackish or bronzed, with but slight metallic lustre C. suturalis ignicauda Deyrolle 6(3) Elytra bluish-black, sharply contrasting with bright greenish-blue pronotum

C. nigripennis Deyrolle

Relatively unadvanced development of pronotal foveae, not caudate elytra without depressions, and simple pattern of colouration suggest, that Suturalis - circle is one of the most ancient groups of Cyphogastra Deyrolle - the common ancestor of the nomi­native subgenus belonged probably here. This ancestral species - evolved from the "pro-to-Cyphogastra" as described in the first paper of the present series (Holynski 1992) -might have been a medium-sized (ca 30 mm long) beetle with distinctly elevated but not very high abdominal plaque, rather coarse elytral sculpture, distinctively punctured bot­tom spaces in pronotal foveae feebly developed, parallel or slightly convergent pronotal sides without accentuated anterior angles, and not or very slightly caudate elytra with truncate apex. It was apparently polymorphic in dorsal colouration, with brightly metallic (green to coppery) and black variants (in the former the elytral suture was either conco-

lorous or contrastingly blue); underside seems to have been always metallic (green, gol­den, or coppery).

It had apparently been distributed all-over New Guinea, until the emergence of the New Guineán Mountains separated the northern populations from those inhabiting the southern part of the area. To the north of Central Range, bottom surfaces within the pronotal foveae grew broad and the colouration of the body became invariably green -this form gave rise to the Mniszechi and Gloriosa circles, now widely distributed between Celebes and Samoa. On the south, elytral punctulation declining towards apex, ventrally green variant almost disappeared, and the elytral suture got standardized as contrastingly blue in non-black individuals. This was already unmistakable representative of the Sutu­ralis - circle - indeed, it is difficult to find any feature to distinguish between so reconst­ructed ancestor from the modern C. suturalis (Fabricius) s.str.! Expansion to the west and east resulted in its distribution over the vast area between Moluques and New Heb­rides.

The invasion of the Gloriosa - circle to the Solomon Islands caused, as it seems, buth the extinction of "proto-suturalis" from there and, consequently, the isolation of the New Hebridean population, which have evolved into big, black above and coppery-red below, very distinctive by its extremely developed abdominal plaque, "zoogeographical relict" -C. tuberculata Thomson.

The evolution of the "mainland" New Guineán populations led - through broadening of the distinctive bottom areas in the pronctal foveae, development of distinctly "cauda­te" shape of elytra, disappearance of black morphs and of those with blue elytral suture, darkening of the pronotum, etc. - to the Albertisi - circle. On the Buruan Archipelago the elytral colouration got fixed as black with a bronzed latero-preapical band, that of the undersurface as green, and the pronotum became bright blue, giving rise to C.nigri­pennis Deyrolle. A t an initial stage of its evolution, this lineage sent an offshoot to the south, which - developing strongly caudate elytra, prominent anterior angles of the pro­notum, greenish diffuse patches on elytral sides, etc. became - the ancestor of the Java-nica - circle.

The phylogenetical reconstructions outlined above, highly speculative as they are, seem nevertheless much more parsimonious than any alternative I can think of. Now, however, we find ourselves left with the Moluccan "core" of the "proto-suturalis" - the essentially unchanged remnant of the common ancestor of the Suturalis - circle - further evolution of which can be conceived on various ways, none being much more likely than the others. For some rather vague reasons I prefer the following scenario, involving two isolation-events and a reinvasion. At first, the Northern Moluccan (Halmahera and adjacent is­lands) population developed the distinctive features of C. s. ignicauda Deyrolle (uni­formly punctured proepisterna, distinctive bottom areas in pronotal foveae, dark tarsi), while that of the southern islands (Ceram, Amboina, etc.) remained without detectable changes as C. suturalis s.str. Then, a small deme of the northern subspecies on one of the islets (Batjan? Ternate?) evolved further - dark dorsal colouration got fixed (founder effect?) and changed from bluish- to brownish-black, undersurface became also blackish, bottom surfaces in the pronotal foveae grew still broader - to make C. carbonaria Théry. A t last, the latter - being reproductively isolated from both races of C. suturalis (Fabri­cius) - reinvaded the areas occupied by them.

The evolutionary history of the Suturalis circle - as reconstructed above - is shown graphically in Fig. 1 (the length of the lines connecting each form with its ancestor is intended to reflect approximately the degree of differentiation).

Jaranica c.

Proto-Cyphogastra

Fig. 1. - Phylogenetic relations in the Suturalis-circle

References

Deyrolle, H (1864): Description des Buprestides de la Malaisie recueillis par M. Wallace -Ann.Soc. Ent.Belg. 8:1-272.

Holynski, R (1992): Taxonomic notes on Cyphogastra Deyrolle. (Col: Bupr.). I . The sub­genus Guamia Théry - Folia ent.hung.

Obenberger, J. (1922): Beiträge zur Kenntnis der Buprestidae (Col.) - Arch.Natg. 88 (A), 12:64-168.

Obenberger, J. (1926): Buprestidae I - Col.Cat. 84:1-212. Théry, A (1926): Recherches synonymiques sur les Buprestides et descriptions d'espèces

nouvelles - Ann.Bull.Soc.Ent.Belg. 66:33-74.

Author's address: Roman HOLYNSKI H-5540 Szarvas Tanya I : 10 (HAKI Lakótelep) HUNGARY