Monomorium subopacum (Smith)

Heterick, B. E., 2006, A revision of the Malagasy ants belonging to genus Monomorium Mayr, 1855 (Hymenoptera: Formicidae)., Proceedings of the California Academy of Sciences 57, pp. 69-202: 103-107

publication ID


persistent identifier

treatment provided by


scientific name

Monomorium subopacum (Smith)


Monomorium subopacum (Smith)  HNS 

Figs. 16, 42-43.

Myrmica subopaca Smith  HNS  1858:127.

Monomorium subopacum (Smith)  HNS  : Mayr 1862:753. Syntype [[worker]]"s,"s, (lectotype here designated) Madeira (BMNH) [examined].

Monomorium (Xeromyrmex) subopacum (Smith)  HNS  : Wheeler W.M. 1922:871.

[ Xeromyrmex  HNS  a junior synonym of Monomorium  HNS  : Ettershank 1966:82].

Myrmica glyciphila Smith  HNS  1858: 125. Syntype [[worker]]"s, (lectotype here designated) Sri Lanka (BMNH) [examined]. Syn. under M. subopacum (Smith)  HNS  : Bolton 1987:360.

Monomorium mediterraneum Mayr  HNS  1861:72 (diagnosis in key). Syntype [[worker]] (see comments below - lectotype here designated) Spain: Cadiz (NMW) [examined]. Syn. under M subopacum (Smith)  HNS  : Mayr 1862:763.

Monomorium (Xeromyrmex) salomonis subsp. subopacum var. senegalensis Santschi  1913: 306 Syntype [[worker]]"s, Senegal: Saint-Louis (NHMB) [not seen] [Unavailable name]. Syn. under M subopacum (Smith)  HNS  : Bolton 1987: 360 (along with proposed replacement names claveaui Emery  1922:178 and santschiellum Wheeler  HNS  , W.M. 1922: 872). See also comment under liberta, below.

Paraphacota surcoufi Santschi  HNS  1919a:90, fig. 1. Syntype [[male]]"s (lectotype here designated), Algeria: Biskra (NHMB) [examined].

Monomorium subopacum v. surcoufi Santschi  1927:243. Syn. under M subopacum (Smith)  HNS  : Bolton 1987:360.

Paraphacota cabrerai Santschi  1919b:405, fig. 1. Holotype [[male]], Canary Isl: Tenerife, Laguna (NHMB) [examined].

Monomorium subopacum var. cabrerai Santschi  1927:241. Syn. under M. subopacum (Smith)  HNS  : Bolton 1987:360.

Paraphacota cabrerae [sic] st. obscuripes Santschi  HNS  1921a:169. Syntype [[male]]"s (lectotype here designated), Canary Isl., Tenerife, Bajamar (NHMB) [examined]. Syn. under M subopacum Santschi  HNS  1927:241.

Monomorium (Xeromyrmex) subopacum var. intermedium Santschi  HNS  1927:242 Syntype [[male]]"s (see comments below -lectotype here designated), Canary Islands, Haria, Lanzarote (MCZ) [examined]. [First available use of Monomorium (Xeromyrmex) salomonis subsp. subopacum var. intermedium Wheeler  HNS  1927:108; unavailable name]. Syn. under M. subopacum (Smith)  HNS  : Hohmann et al. 1993:155.

Monomorium (Xeromyrmex) subopacum var. apuleii Santschi  HNS  1927:243. Syntypes [[worker]], [[queen]], [[male]], Tunisia: Hammamat (?NHMB) [not seen].

Monomorium (Xeromyrmex) subopacum var. liberta Santschi  HNS  1927:243. [First available use of Monomorium (Xeromyrmex) salomonis subsp. subopacum st. liberta Santschi  HNS  1921c:170; unavailable name]. Syn. under M. subopacum Bolton  HNS  1987: 360. (NB. M. liberta syntypes  HNS  are same specimens as senegalensis  HNS  above).

Monomorium (Xeromyrmex) subopacum var. ebraicum Menozzii  HNS  1933:62. Syntypes [[worker]], [[male]], Israel: Tel Aviv (?Instituto di Entomologia, Universita di Bologna "Guido Grandi" [IEGG]) [not seen]. Nominal subspecies of M subopacum Bolton  HNS  1995:261.

Monomorium (Xeromyrmex) subopacum var. adoneum Santschi  HNS  1936:41, fig. 22 [spelled "adonis" under fig.]. Syntype [[worker]]"s, Lebanon: Djbeil ou Djbla (?NHMB) [not seen]. Nominal subspecies of M.subopacumBolton 1995:258.

Monomorium (Xeromyrmex) subopacum subsp. italica Baroni  HNS  Urbani 1964:154, figs. 2-3. Holotype [[worker]], Italy: Gambarie (not seen) (Museo Civico di Storia Naturale di Verona [MSNV]) [not seen]. Syn. under M. subopacum(Smith)  HNS  : Baroni Urbani 1968:450.

Material examined.- M. subopacum  HNS  : Lectotype: [[worker]], Madeira, TV. Wollaston (BMNH). In view of the subtle differences that separate genuine good species in the M. salomonis  HNS  group, I am designating a lectotype to fix the name " subopacum  HNS  ", the type worker material of which is a richer reddish brown than the type material for M. glyciphilum. The syntype material is on a single card rectangle. The lectotype worker is the third worker from the RHS, seen from the rear. Paralectotypes: Three workers and three queens, carded on the same rectangle as the holotype (BMNH). No attempt has been made to separate the ants. M. glyciphilum: Lectotype: [[worker]], Sri Lanka ("Ceylon"), no collector named (BMNH). The syntype material seen (three carded workers) is darker than that of M. subopacum  HNS  . The lectotype is the RHS specimen (seen from the rear). The rationale for choosing a lectotype is given above under M. subopacum  HNS  . Paralectotypes: Two workers on the same card as the lectotype (BMNH). No attempt has been made to separate the workers. M. mediterraneum  HNS  : Lectotype: I have seen five specimens labeled "type" (NMW). These comprise four workers and one queen. The collection locality reads "Rotes Meer" (Red Sea), collector (the queen, at least) Frauenfeld (handwritten label). I have also inspected four additional workers, not labeled "type". One worker, from Cadiz (Spain), coll. (?)Rogenhofer (partly illegible handwriting), (NMW) also possesses a label indicating it was seen by Mayr in 1862, and I think it reasonable to assume it was one of the specimens, possibly a M. mediterraneum  HNS  syntype, examined by that researcher when he synonymized mediterraneum  HNS  with subopacum  HNS  in the same year. A third label reads "Monom. subopacum  HNS  det. Mayr". Two of the remaining workers carry only the determination label, while the third has an additional slip: "Frfld Rothes [sic] Meer 1855". The label data presents a conundrum: all nine workers are not only morphologically identical but have been mounted in identical fashion; i.e., one ant glued lengthwise at the end of a point so its head overhangs the apex of the triangle. Even the points, pins and glue are identical. The queen is mounted in similar fashion. The handwriting on the four specimens not designated"type", however, is that of a different person to the one who labeled the five specimens designated "type".

There are not sufficient data in either Mayr"s original description or on the labels to answer the question of the type status of these specimens definitively. Mislabeling, possibly by an assistant, also appears to have occurred. The original description, however, does reveal that Mayr examined one queen and multiple workers from southern Spain. In the interests of the stability of the name mediterraneum, and based on the likelihood that it is in fact part of the original type series, I am designating the Cadiz specimen a lectotype. Monomorium surcoufi  : Lectotype: [[male]], Algeria, Biskra, August 1919, at light ("a la lumiere") (NHMB - Reg. No. 213). The lectotype (top rectangle) fixes the name for this taxon in which the clypeus and male reproductive structures are said by Santschi to differ from those of M. cabrerai  which has similarly colored legs. Paralectotype: [[male]], on same pin as the lectotype and with same data (NHMB - Reg. No. 213). Monomorium cabrerai  : Holotype: [[male]], Canary Isl., Tenerife, Laguna, 25.VII.1903. [Published collector A. Cabrera y Diaz] (NHMB - Reg. No. 213). This male was designated a "holotype" by Bolton (1987), and since the length is given as single measurement, it seems clear no other specimens were examined. Bolton"s 1987 revision is therefore deemed to have given this specimen support for a holotype status (Code 73.1.2). Nb.: the labels on both this specimen and the type specimens of its putative subspecies "obscuripes" read "cabrerae", but in the published description of the former the rendition is M. " cabrerai  " and that of the supposed subspecies is "M. cabrerae". All of this is part of the general confusion and inconsistent taxonomy that has bedeviled this species. Since the worker after whom the ant was named was presumably a male (the Christian name of A. Cabrera y Diaz was "Anatael"), "cabrerai" should be the correct spelling, and is followed here. However, researchers have generally adopted "cabrerae", as per the labels (e.g., Wheeler 1922; Bolton 1995 - but see Bolton 1987). Monomorium cabrerai obscuripes  : Lectotype: [[male]], Canary Isl., Tenerife, Bajamar, 10.X.1909, A. Cabrera (NHMB - Reg. No. 213). The designation of a lectotype fixes the name for this taxon in which the male has uniformly dark legs. Paralectotype: [[male]], same locality as lectotype, 20.IX.1909 (NHMB - Reg. No. 213). Monomorium subopacum intermedium  : Lectotype: [[worker]], Canary Islands, Haria, Lanzarote, 1000 ft, 8 Jan. 1925 ["8. 1. 25"] W.M. Wheeler. MCZ cotype [syntype] 3-5 20875 (MCZ). The lectotype fixes the taxon name for populations of M. subopacum  HNS  found on the Canary Islands. The lectotype worker has been repinned with the original labels. The subgenus Xeromyrmex  HNS  represents an outmoded way of looking at Monomorium  HNS  species related to the M. salomonis  HNS  group, and the possibility of its use being revived is highly remote, to say the least (see Bolton 1987), even if intermedium  HNS  is brought out of synonymy in the future. Paralectotypes: Ten workers (several damaged) with the same collection data as the lectotype (MCZ). Two workers, originally on the same pin as the lectotype, have been repinned with photocopies of the original labels. NB. The original syntype series of 43 workers included a worker of another species, whose appearance agrees with the description of Monomorium medinae Forel  HNS  (type material not seen). This is a member of the M. salomonis  HNS  group, endemic to the Canary Islands (Bolton 1987), in which the body sculpture of the worker is largely effaced. I have repinned this worker with photocopies of the original labels and an additional label stating that it does not belong to the taxon Monomorium subopacum var. intermedium Santschi  HNS  .

Other material examined: Prov. Toliara: Sakaraha, 15.ii.1993 P.S. Ward 11937.5773/4 (3 [[worker]]) (MCZ) 11937 (3 [[worker]]) (UCDC) 11932 (3 [[worker]]) (UCDC).

Worker description.- Head: Head rectangular; vertex planar or weakly concave; frons shining and finely microreticulate; pilosity of frons consisting of abundant, incurved, appressed setulae only. Eye large, eye width 1.5 x greater than greatest width of antennal scape; eyes (in fullface view) set at about midpoint of head capsule; (viewed in profile) eyes set around midline of head capsule; elliptical, curvature of inner eye margin may be more pronounced than that of its outer margin. Antennal segments 12; club three-segmented. Clypeal carinae indicated by multiple weak ridges; anteromedian clypeal margin emarginate, clypeal carinae terminating in blunt angles; paraclypeal setae moderately long and fine, curved; posteromedian clypeal margin approximately level with antennal fossae. Anterior tentorial pits situated nearer antennal fossae than mandibular insertions. Frontal lobes straight, parallel. Psammophore absent. Palp formula 2,2. Mandibular teeth four; mandibles with sub-parallel inner and outer margins, striate; masticatory margin of mandibles approximately vertical or weakly oblique; basal tooth approximately same size as t3 (four teeth present).

Mesosoma: Promesonotum shining and microreticulate throughout; in profile broadly convex anteriad, convexity reduced posteriad; promesonotal setae absent; appressed promesonotal setulae well-spaced over entire promesonotum. Metanotal groove weakly to strongly impressed, with distinct transverse costulae. Propodeum shining and microreticulate; propodeal dorsum flat throughout most of its length; angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity between 2:1 and 4:3; standing propodeal setae absent; appressed propodeal setulae wellspaced and sparse; propodeal spiracle nearer metanotal groove than declivitous face of propodeum; vestibule of propodeal spiracle absent or not visible; propodeal lobes present as rounded flanges.

Petiole and postpetiole: Petiolar spiracle lateral or laterodorsal and situated within anterior sector of petiolar node. Node (viewed in profile) cuneate, vertex rounded, or, conical, vertex rounded; appearance of node shining and distinctly microreticulate; ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) between 1:1 and 3:4. Anteroventral petiolar process present as a thin flange tapering posteriad; ventral petiolar lobe present, but weakly developed to vestigial. Height ratio of petiole to postpetiole between 3:2 and 4:3; height -length ratio of postpetiole between 1:1 and 3:4; postpetiole shining and microreticulate; postpetiolar sternite without anterior lip or carina, or this structure vestigial.

Gaster: Pilosity of first gastral tergite consisting mainly of short, appressed setulae, together with one to several pairs of erect and semi-erect setae.

General characters: Color mesosoma, nodes and legs orange-yellow, head and antennae brown, gaster dark brown. Worker caste monomorphic.

Lectotype measurements ( M. subopacum  HNS  ): HML 1.81 HL 0.67 HW 0.54 CeI 81 SL 0.56 SI 104 PW 0.35.

Lectotype measurements ( M. glyciphilum  HNS  ): HML 2.03 HL 0.72 HW 0.60 CeI 83 SL 0.62 SI 104 PW 0.39.

Lectotype measurements ( M. mediterraneum  HNS  ): HML 1.92 HL 0.70 HW 0.55 CeI 79 SL 0.58 SI 105 PW 0.36.

Lectotype measurements ( M. subopacum intermedium  ): HML 1.93 HL 0.71 HW 0.58 CeI 82 SL 0.59 SI 102 PW 0.36.

Other worker measurements (non-types): HML 1.77-2.12 HL 0.64-0.73 HW 0.52-0.61 CeI 80-85 SL 0.54-0.64 SI 104-108 PW 0.34-0.42 (n=9).

Queen description (based on three paralectotype queens of " Monomorium subopacum  HNS  " and one queen of " Monomorium mediterraneum  HNS  ").- Head: Head square; vertex always planar; frons shining and finely longitudinally striolate and microreticulate; pilosity of frons consisting of wellspaced appressed setulae only. Eye roundly elliptical; in full-face view, eyes set above midpoint to of head capsule; in profile, eyes set posteriad of midline of head capsule.

Mesosoma: Anterior mesoscutum smoothly rounded, thereafter more-or-less flattened; pronotum , mesoscutum and mesopleuron uniformly finely punctate-microreticulate; length-width ratio of mesoscutum and scutellum combined between 2:1 and 3:2. Axillae narrowly separated (i.e., less than width of one axilla). Standing pronotal/mesoscutal setae sparse or absent; appressed pronotal, mescoscutal and mesopleural setulae well- spaced over entire pronotum/mesonotum. Propodeum entirely microreticulate-striolate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum slightly elevated anteriad and sloping away posteriad, propodeal angles not raised; standing propodeal setae absent; appressed propodeal setulae well-spaced and sparse; propodeal spiracle nearer metanotal groove than declivitous face of propodeum; propodeal lobes present as well-developed, rounded flanges or bluntly angled flanges.

Wing: Wing not seen (queens dealated).

Petiole and postpetiole: Petiolar spiracle lateral and situated within anterior sector of petiolar node; node, in profile, cuneate, vertex rounded; appearance of node matt and microreticulate, rugose posteriad; ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) about 1:1. Anteroventral petiolar process present as a thin flange tapering posteriad; height ratio of petiole to postpetiole between 3:2 and 1:1; height -length ratio of postpetiole between 4:3 and 1:1; postpetiole shining and microreticulate; postpetiolar sternite without anterior lip or carina, or this structure vestigial.

Gaster: Pilosity of first gastral tergite consisting of long, appressed setae and one or two semierect setae, or, standing setae completely absent.

General characters: Color tawny, variegated brown. Brachypterous alates not seen. Ergatoid or worker-female intercastes not seen.

Queen measurements: HML 3.13-3.43; HL 0.91-0.92; HW 0.79-0.86; CeI 89-93; SL 0.70-0.79; SI 89-92; PW 0.68-0.74 (n=4).

Male.- I have only seen damaged male specimens (lectotypes for the taxa Monomorium surcoufi, M. cabrerai and M. cabrerai obscuripes  ). As there has been controversy over the assignment to M. subopacum  HNS  of at least the males of Monomorium cabrerai obscuripes  and the other males are tattered and lack body parts, no formal description of the abovementioned males is included here.

Male Type Measurements: Lectotype measurements ( Monomorium surcoufi  ): HL 0.88 HW 0.98 CeI 111. (NB. Lectotype lacks antennae, postpetiole and gaster). Holotype measurements ( Monomorium cabrerai  ): HML (Holotype lacks postpetiole and gaster) HL 0.89 HW 0.96 CeI 108 SL 0.29 SI 30 PW 1.00. Lectotype measurements ( Monomorium cabrerai obscuripes  ): HML 3.17 HL 0.79 HW 0.86 CeI 109 SL 0.30 SI 35 PW 0.80.

Remarks.- Bolton (1987) recognized this species from Madagascar on the basis of a short series from Maevatanana ("Maevantanara"); however, there are no Malagasy specimens in the CAS, despite the huge amount of Monomorium  HNS  material collected by Brian Fisher and his teams since the early 1990s. The Malagasy component in the description and measurements provided above includes details from six specimens held at UCDC and three specimens from the same series held at MCZ. Monomorium subopacum  HNS  is very similar to Monomorium willowmorense  HNS  (below), but those worker specimens I have seen of the former can be distinguished from M. willowmorense  HNS  by their finely granulate-reticulate frons, uniformly sculptured promesonotal humeri and a longer antennal scape (SI> 100 in M. subopacum  HNS  and <100 in M. willowmorense  HNS  ). Nonetheless, the differences that separate the two are small, and in view of the variability to be found in M. subopacum  HNS  (note the voluminous entries above!) I would not be surprised if molecular -based investigations resulted in M. willowmorense  HNS  being added to the already overburdened synonymic list for M. subopacum  HNS  .

Several of the synonyms are those of taxa originally described from males. The spurious genus " Paraphacota  HNS  " incorporated three such taxa, and what appears to me to be two distinct species. The male of Monomorium surcoufi  and that of M. cabrerai  are obviously identical, and easily recognized by their long, bicolored legs and completely hyaline wings. On the other hand, the male of Monomorium cabrerai obscuripes  has relatively shorter, uniformly dark legs and brown wing veins. I have not seen nest material of Monomorium subopacum  HNS  that has included males, but Bolton (1987) was in no doubt that the descriptions of M. surcoufi  and M. cabrerai  were based on ordinary males of M. subopacum  HNS  . He followed Santschi in also placing M. cabrerai obscuripes  under M. subopacum  HNS  but allowed that it could be the male of M. medinae Emery  HNS  , a Canary Islands endemic, a view first broached by Wheeler (1927). Hohmann et al. (1993) included the two cabrerai  taxa under Monomorium medinae  HNS  , but omitted Monomorium surcoufi  . This seems to me an odd judgement, and, indeed, Bolton (1995) did not mention these authors at all in relation to " Paraphacota  HNS  ", but continued to consign all three taxa to synonymy under Monomorium subopacum  HNS  . (NB. Dr. Xavier Espadaler [pers. commun.] also places M. cabrerai  under M. subopacum  HNS  , leaving M. cabrerai obscuripes  as an unresolved puzzle, but has indicated that none of the males originally placed under " Paraphacota  HNS  " belongs to Monomorium medinae  HNS  .)

Monomorium subopacum  HNS  , like Monomorium pharaonis  HNS  , is something of a tramp, and its occurrence in Madagascar and other regions well away from its natural area of occurrence is certainly due to human activities (Bolton 1987).