Colobopsis Mayr 1861

Ward, Philip S., Blaimer, Bonnie B. & Fisher, Brian L., 2016, A revised phylogenetic classification of the ant subfamily Formicinae (Hymenoptera: Formicidae), with resurrection of the genera Colobopsis and Dinomyrmex, Zootaxa 4072 (3), pp. 343-357 : 350-351

Colobopsis Mayr 1861 stat. rev.

Type species: Formica truncata , designated by Bingham (1903: 342).

Myrmogonia Forel (as subgenus of Camponotus ). Type species Camponotus laminatus , designated by Wheeler (1913: 81). Syn. n.

Dolophra Wu & Wang. Type species Dolophra politae , by original designation. Junior synonym of Camponotus: Bolton (1995: 27) ; of Camponotus (Colobopsis) : Bolton (2003: 113).

Diagnosis, minor worker. Generally small, HW 0.65–1.10 (exceptions: cylindrica group and the Fijian radiation, where HW 0.90–1.70), with rounded head and relatively small eyes, REL 0.20–0.32; head width three-quarters of more of head length (CI 0.75–0.98; except one Fijian species, C. polynesica , where CI ~0.72); antennal insertions—and hence also the frontal carinae—relatively relatively well separated, ASM/HW 0.36–0.47 (except cylindrica group, New Caledonia radiation and the Fijian radiation, where ASM/HW 0.31–0.39), ASM/CLW usually 0.66–0.98 (except some New Caledonian and most Fijian species where ASM/CLW is in the range of 0.60– 0.66); frontal carinae relatively short, usually not strongly sinuate, the antennal insertions occurring at about midlength of the frontal carinae; clypeus more or less subquadrate, as long as wide or slightly wider than long (CLW/CLL 0.96–1.32), with sides parallel or diverging moderately towards the anterior margin (clypeus broader in Fijian species of the bryani and dentata groups where CLW/CLL ~ 1.46, and in the conica and vitrea groups, sensu Emery (1925), where CLW/CLL 1.40–1.50 and clypeus more trapezoidal in form); anterolateral extremities of clypeus differentiated from rest of clypeus by a sulcus or impression running from the anterior tentorial pit to the clypeal margin, the suture between clypeus and malar region of head often weak here, so that the clypeus appears to lack the anterolateral extensions often conspicuous in Camponotus minors (compare Figures 2–5 with Figure 15 ).

Diagnosis, major worker. Head generally phragmotic, varying from strongly truncate and marginate ( Figure 6 ) to weakly truncate ( Figure 7 ), the truncated portion incorporating part of the clypeus, the malar region of the head capsule and the upper surface of the mandibles. Clypeus elongate-rectangular, the anterolateral extremities separated from the clypeus by a well-marked sulcus and appearing to form an independent triangular sclerite.

Additional diagnostic features. Dimorphic worker caste, with few or no intermediates between major and minor workers, except in the cylindrica group ( Emery 1925); larva with distinctive ventral trough (praesaepium), overhung posteriorly by a protruding welt of the second abdominal segment ( Wheeler & Wheeler 1953, 1982); pupa naked ( Wheeler 1904). Brendon Boudinot has recently found that male Colobopsis have distinctive genitalia, with the shape of the digitus distinguishing them from Camponotus males (Boudinot, in prep.).

The elevation of Colobopsis to the rank of genus generates the following new combinations (unless noted as revived) in Colobopsis : abdita, anderseni , annetteae, aruensis , aurata, aureliana, badia (unresolved junior primary homonym), badia saginata, brachycephala , † brodiei , bryani , calva, camela , cerberula, ceylonica , clerodendri , conica (comb. rev.), conithorax , corallina (comb. rev.), cotesii , cristata, culmicola , culmicola haweisi, custodula, cylindrica (comb. rev.), dentata (comb. rev.), desecta (comb. rev.), elysii , equa, etiolata , excavata, fijiana, flavolimbata, gasseri (comb. rev.), gundlachi , guppyi , horrens , horripila, hosei , hosei mima, howensis , hunteri , impressa (comb. rev.), kadi, karawaiewi , laminata , laotsei, lauensis , leonardi , leonardi gracilenta, leonardi grisea, levuana, loa , loa belli, longi , maafui , macarangae , macrocephala , manni , markli, mathildeae , mississippiensis , mutilata, mutilata stitzi, newzealandica, nigrifrons (comb. rev.), nipponica, obliqua, oceanica , papago , perneser , phragmaticola , politae , polynesica , pylartes , pylartes fraxinicola, pylora, quadriceps , quadriceps convexior, quadriceps curvata, quadriceps nanula, reepeni , riehlii (comb. rev.), rothneyi , rothneyi krafti, rothneyi makilingi, rothneyi taivanae, rotunda, rufifrons (comb. rev.), rufifrons leucopa, sadina, sanguinifrons , saundersi , saundersi krama, schmeltzi , schmitzi , severini , shohki, smithiana, solenobia, sommeri (comb. rev.), stricta (comb. rev.), trajana, tricolor (comb. rev.), triton , truncata (comb. rev.), umbratilis, vitiensis , vitrea, vitrea angustula, vitrea carinata , vitrea latinota (unresolved junior primary homonym), vitrea oebalis, vitrea praelutea, vitrea praerufa, vitrea vittatula, and wildae .

Comments. As now conceived the genus Colobopsis comprises 94 valid species (93 extant, 1 fossil) and 23 subspecies. Based on original descriptions and images, Camponotus bifossus and Camponotus tritschleri , nominally Colobopsis , are retained in Camponotus , subgenus indeterminate; and Camponotus cordincola is retained in Camponotus , and transferred to subgenus Pseudocolobopsis . The eight Fijian species in the subgenus Myrmogonia ( Sarnat & Economo 2012) are transferred to Colobopsis , based on both genetic (e.g., Clouse et al. 2015) and morphological evidence. Three Australian species, armstrongi , cameratus , and macareaveyi , previously assigned to subgenus Myrmogonia , are retained in Camponotus , subgenus indeterminate. McArthur’s (2012) treatment of Colobopsis , which involved numerous ad hoc and poorly justified transfers of species from other Camponotus subgenera into Camponotus (Colobopsis) , is here ignored.

Biology. Most species of Colobopsis are strictly arboreal, nesting in cavities in dead branches or twigs and employing phragmotic major workers to block the nest entrance ( Forel 1892; Wheeler 1904; Creighton 1967). In some Fijian species, with reduced phragmosis, nests can also be found in rotten wood and in epiphytic ant-plants ( Sarnat & Economo 2012). Phragmosis is also reduced in some Southeast Asian species nesting in live stems; at least one species, Colobopsis macarangae , apparently lacks a major worker subcaste ( Dumpert 1996). In the field, collections of Colobopsis can be readily distinguished from those of Camponotus if pupae are available: these are always naked in Colobopsis ( Wheeler 1904; Ward, pers. obs.), while those of Camponotus are enclosed in cocoons.

Distribution. Colobopsis occurs in the New World from southern United States to Costa Rica; across the southern and central Palearctic from the western Mediterranean to Japan; throughout the Oriental and Australian biogeographic regions as far south as Tasmania; and into the Pacific as far east as New Caledonia, Vanuatu, and Fiji. The genus is notably absent from the Afrotropics and most of the Neotropics.

Distinguishing Colobopsis from Camponotus . Despite their phylogenetic distance, morphological distinctions between Colobopsis and Camponotus have been obscured by extensive evolution within each group, including convergent evolution of phragmotic heads in the major workers of some Camponotus , and variable development of phragmosis in Colobopsis ( Figures 5–6 ). Some recent taxonomic treatments have confused the two lineages. For example, of the 11 species assigned by McArthur & Shattuck (2001) to the “ Camponotus macrocephalus group” eight are Colobopsis ( anderseni , annetteae, conithorax , gasseri , howensis , macrocephala , sanguinifrons , vitrea) and three are Camponotus ( janeti , janforrestae, mackayensis). Similarly, of the four newly described species of phragmotic “ Camponotus ” from New Guinea in Klimes & McArthur (2014), one is Colobopsis (rotunda), while the other three are Camponotus .

To reduce future confusion we provide a key for separating minor workers of Colobopsis from those of Camponotus . It is helpful to segregate the New Caledonian and Fijian species, since Colobopsis tends to “break the rules” in these island situations ( Figures 8–13 ).

1 Not occurring in Fiji or New Caledonia................................................................... 2 - Occurring in Fiji..................................................................................... 3 - Occurring New Caledonia.............................................................................. 4 2 Generally small species, HW 0.65–1.10 (except cylindrica -group of Southeast Asia with HW 1.20–1.70, and facies as in Figures 4 and 5); either antennal insertions relatively well separated, such that ASM/HW 0.36–0.47 and ASM/CLW 0.66–0.98, and/or clypeus relatively narrow, such that CLW/CLL 0.96–1.32; antennal insertions occurring at about midlength of frontal carinae; anterolateral extremities of clypeus set off from rest of clypeus by a sulcus or impression, so clypeus appears to lack prominent anterolateral extensions ( Figures 2–5 ).................................................... Colobopsis - Small to large species, HW 0.70–3.00; antennal insertions less well separated, such that ASM/HW 0.22–0.35 and ASM/CLW 0.35–0.68; clypeus variable in shape but in smaller species with HW 0.70–1.35 (e.g., Camponotus (Myrmamblys) , C. ( Myrmentoma ) and C. ( Pseudocolobopsis )) clypeus tending to be relatively broad, such that CLW/CLL 1.25–1.62, although exceptions occur (e.g., in some C. ( Pseudocolobopsis ) species) ( Figures 14–15 ); antennal insertions usually occurring in front of midlength of frontal carinae; clypeus typically with prominent anterolateral extensions ( Figure 15 )........... Camponotus 3 With conspicuous long setae, gracile legs, and a shield-shaped clypeus with prominent anterolateral extensions ( Figure 16 ).................................................................................... Camponotus chloroticus - Without the combination of conspicuous long setae and gracile legs; clypeus lacking prominent anterolateral extensions (Figures 8–11).................................................................................. Colobopsis 4 Small species, HW 0.68–1.04; antennal insertions more widely separated (ASM/HW 0.34–0.39 and ASM/CLW 0.64–0.77) ( Figures 18–19 ); clypeus tending to be less broad (CLW/CLL 1.15–1.40)................................. Colobopsis - Small to medium-sized species, HW 0.75–2.10; antennal insertions less well separated (ASM/HW 0.25–0.29 and ASM/CLW 0.46–0.55); clypeus varying in shape, but if HW <1.0 5 (e.g., Camponotus pulchellus complex) ( Figure 17 ) then clypeus tending to be broader (CLW/CLL 1.25–1.60)......................................................... Camponotus

Figures

FIGURES 2 – 7. Selected species of Colobopsis, full-face view of head of minor worker (Figs. 2 – 5) and lateral view of soldier (Figs. 6 – 7). 2, Colobopsis etiolata, Texas, USA (CASENT 0104949); 3, C. truncata, Bulgaria (CASENT 0179881); 4. C. cylindrica group, Brunei (CASENT 0280269); 5, C. quadriceps, Papua New Guinea (CASENT 0280264); 6, C. truncata, Italy (CASENT 0249998); 7, C. quadriceps, Papua New Guinea (CASENT 0280263). Images from AntWeb (www. antweb. org); photographers Aprile Nobile (2), Erin Prado (3), Estella Ortega (4, 5, 7) and Ryan Perry (6).

FIGURES 14 – 19. Selected species of Camponotus (Figs. 14 – 17) and New Caledonia Colobopsis (Figs. 18 – 19), full-face view of head of minor worker. 14, Camponotus (Pseudocolobopsis) claviscapus, Costa Rica (CASENT 0249388); 15, C. (Myrmentoma) decipiens, Texas, USA (CASENT 0249367); 16. C. (Tanaemyrmex) chloroticus, Fiji (CASENT 0171139); 17, C. (Myrmamblys) pulchellus _ cf, New Caledonia (CASENT 0280237); 18, Colobopsis indet. (CASENT 0280248); 19, Colobopsis camela (CASENT 0280242). Images from AntWeb (www. antweb. org); photographers Will Ericson (14 – 15), Eli Sarnat (16) and Shannon Hartman (17 – 19).

FIGURES 8 – 13. Species of Colobopsis from Fiji. Full-face view of head of minor worker (Figs. 8 – 11) and lateral view of minor worker (Figs. 12 – 13). 8, Colobopsis vitiensis (CASENT 0280250); 9, C. polynesica (CASENT 0280252); 10. C. schmelzi (CASENT 0280259); 11, C. bryani (CASENT 0280258); 12, C. schmelzi (CASENT 0280259); 13, C. bryani (CASENT 0280258). Images from AntWeb (www. antweb. org); photographers Shannon Hartman (8 – 9) and Estella Ortega (10 – 13).