Sericomyrmex parvulus Forel, 1912

Jesovnik, Ana & Schultz, Ted R., 2017, Revision of the fungus-farming ant genus Sericomyrmex Mayr (Hymenoptera, Formicidae, Myrmicinae), ZooKeys 670, pp. 1-109 : 72-76

Sericomyrmex parvulus Forel, 1912 Figures 48, 49(Worker); Figure 49(Queen); Figure 50(Larva); Figure 47 (Map)

Sericomyrmex parvulus Forel, 1912: 193. Lectotype worker (here designated): BRAZIL, Pará, [-4, -53] C. Emery (MHNG: 1w, USNM00445579, bottom specimen). Paralectotype: same data as lectotype (MHNG: 1w, USNM00445579, top specimen).

Sericomyrmex myersi = Weber, 1937: 400. syn. n. Type material examined: SURINAME, Nickerie, Upper Courantyne River, JGM5931, 29 Dec 1935, J. G. Mayers (MCZ: 1w, USNMENT00924107).

S. parvulus worker diagnosis.

Small species; posterior cephalic corner smoothly rounded; frontal lobe triangular, small, narrow; frontal carina faint, incomplete; mesosomal tubercles small, low, first gastral tergite with lateral carinae weakly developed, dorsal carinae absent.

S. parvulus worker description.

Measurements in mm, range (lectotype): HWe 0.66-0.9 (0.9) HW 0.66-0.93 (0.93) HW1 0.6-0.93 (0.84) HW2 0.68-1.03 (0.93) HW3 0.48-0.8 (0.6) IFW1 0.42-0.65 (0.62) IFW2 0.15-0.28 (0.26) HL1 0.62-0.9 (0.88) HL2 0.58-0.82 (0.8) SL 0.48-0.72 (0.64) EL 0.11-0.15 (0.15) Om 6-9 WL 0.74-1.23 (1.23) PL 0.16-0.34 (0.25) PPL 0.13-0.24 (0.16) GL 0.6-0.9 (0.83) HFL 0.65-0.99 (0.92) PW 0.46-0.64 (0.62) CI 94-106 (103) FLI 60-75 (69) SI 64-78 (71) OI 13-19 (17) CEI 5-12 (8) [N=55]

Pilosity. Pubescence dense, lighter than integument, appressed to decumbent. Hairs moderately thick, relatively sparse, often curved, yellow to gray, appressed to suberect.

Head. In full-face view evenly broad and long (CI=102 ± 3), posterior corner smoothly rounded, posterior cephalic emargination shallow (CEI=9 ± 2), gradually impressed. Vertexal impression faint, frontal tumuli barely visible. Mandible with 7-8 teeth, dorsally smooth and glossy, finely transversely striate only along masticatory margin. Eye medium-sized (OI =16 ± 1), flat to slightly convex, 6-9 ommatidia across largest diameter, in some specimens eyes partially covered with white layer (Figure 6l), in others eyes without white layer. Frontal lobe triangular, relatively small and narrow (FLI=70 ± 3), posterior margin shorter than medial. Frontal carina straight to slightly curved laterally, incomplete, weak, fading before reaching posterior cephalic corner. Antennal scape relatively short, not reaching posterior cephalic corner (SI=71 ± 3).

Mesosoma. Mesosomal tubercles low and obtuse. Propodeal carinae low and weak, with small posterodorsal denticles.

Metasoma. Petiole with two low, reduced dorsal denticles; postpetiole with two faint, short dorsal carina; both best seen in dorsolateral view. First gastral tergite with lateral carinae weakly developed, dorsal carinae faint or absent.

S. parvulus queen description.

Measurements in mm, range: HWe 0.98-1.05 HW 1-1.08 HW1 1-1.13 HW2 1.08-1.22 HW3 0.74-0.8 IFW1 0.7-0.78 IFW2 0.24-0.28 HL1 0.95-1.08 HL2 0.88-0.95 SL 0.64-0.7 EL 0.21-0.24 Om 14-15 EW 0.08-0.08 WL 1.56-1.65 PL 0.34-0.48 PPL 0.2-0.25 GL 1.4-1.58 HFL 1-1.18 PW 0.82-0.92 CI 95-103 FLI 72-76 SI 66-70 OI 21-23 [N=4]

Head. Mandible with 7-8 teeth, dorsally glossy and smooth, finely transversely striate only along masticatory margin. Preocular carina fading posterior to eye. Eye large (OI=22 ± 1), mildly convex, 14-15 ommatidia across largest diameter. Frontal lobe more robust than in worker, antennal scape not reaching posterior cephalic corner.

Mesosoma. Lateral pronotal tubercles very low. Scutum in dorsal view with notauli and median mesoscutal line absent or very faint. Parapsidal lines faint, slightly curved. Axillae small, groove separating axillae from scutellum smooth. Scutellum short in dorsal view, narrowing posteriorly, posterior margin with V-shaped notch, notch sometimes continuing into median impression that divides scutellum in two lateral parts. Propodeal denticle low, obtuse, laterally flattened, diverging posteriorly in dorsal view.

Metasoma. First tergite of gaster with lateral carinae well developed, dorsal carinae absent or weak, anteromedian groove shallow.

S. parvulus male.

Unknown.

S. parvulus geographic range.

Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname. Map: Figure 47.

S. parvulus larva.

Lateral and dorsal surfaces without any setae. Supra-antennal setae absent. Four genal setae on each side. Mandibular apical tooth undivided. Labial denticles either absent or small number of denticles present anterior to sericteries. Thoracic segment 1 (T1) ventrally with multidentate spinules. Number of ventral setae: T1, T2, and T3 with two setae each, abdomen without setae (not including anal setae). Single pair of sensilliform setae anterior to anal opening.

S. parvulus notes.

The aptly named S. parvulus is the smallest Sericomyrmex species. In the regions where their distributions overlap (Figure 47), parvulus is most easily mistaken for S. opacus . In general opacus is larger, with wider, rectangular frontal lobes. Similarly, the S. opacus queen can be separated from the parvulus queen by its slightly larger size and by the presence of supraocular eye carinae in some specimens (absent in parvulus ). The queen of S. saramama is similar in size but can be recognized by its striate mandibles (smooth in parvulus ).

Within-species morphological variation in S. parvulus includes the frontal carinae (typically incomplete and faint, but complete and stronger in some populations), eyes (sometimes covered with a white layer, but sometimes not), and the general robustness of denticles and tubercles on the mesosoma and metasoma.

In the populations of S. opacus from southern Colombia and northwestern Brazil (clade opacus 3, see discussion in notes for S. opacus and Suppl. material 1), some of the workers have small, triangular frontal lobes, making them easy to mistake for parvulus . They are usually larger than the typical parvulus worker, but given the overlap in size between the two species, they could be mistaken for larger parvulus workers. It is possible that these intermediate individuals are hybrids and that the molecular and morphological differences between the Colombian and Brazilian populations of opacus are a consequence of hybridization and introgression with parvulus (see also discussion in notes for S. opacus ).

Synonymies. The holotype specimen of S. myersi we examined is almost identical to the parvulus lectotype, except that the tubercles on the mesosoma are slightly more distinct in myersi , but this difference falls well within the variation observed in parvulus . In his description of myersi Weber (1937) distinguishes it from S. lutzi and S. harekulli by its much smaller size but does not compare it to S. parvulus .

S. parvulus material examined.

BOLIVIA: Beni: Cavinas, [-12.5311, -66.9146], 30 Oct 1921, W. M. Mann; Santa Cruz: 10km NW Terevinto, -17.6667, -63.45, 380m, 9 Dec 1993, P. S. Ward; 35 km SSE Flor de Oro, -13.8333, -60.8667, 450m, 27 Nov 1993, P. S. Ward; BRAZIL: Amazonas: Embrapa Amazônia Ocidental, 30 km N Manaus, -2.89824, -59.9903, 4 Sep 2006, C. Rabeling; Manaquiri, Br 319, km100, [-3.6829, -60.32], 10 Oct 2010, F. Baccaro; Manaus, Br 174 Km 46-EEST INPA, [-2.58, -60.03], 83m, 21 Feb 1991, A. Y. Harada; Manaus, Dimona, INPA,100 ha plot, -2.3833, -60.1, 80m, 6 Jan 2009, J. Sosa-Calvo; Manaus, Rs2303, [-2.96, -59.93], 29 Sep 1993, A. B. Casimiro; Pres. Figueiredo, [-2.02, -60.02], 27 Jan 1994, Queiroz; São Gabriel de Cachoeira, [-0.1237, -67.0476], 120m, 23 Aug 1992, T. R. Schultz; Bahia: Ilhéus, Itabuna, CEPEC area Zoolog, km 22, [-14.7, -39.2], 1 Oct 1986, J. H. C. Delabie; Itabuna, Ferradas A27, -14.8258, -39.4044, 21 Sep 2000, J. R. M. Santos; Lençóis, -12.56151, -41.36942 ± 5m, 487m, 10 Nov 2008, J. Sosa-Calvo; Lençóis, trevo, [-12.55, -41.6833], 30 Mar 2001, J. R. M. Santos; Porto Seguro, -16.3925, -39.1694; Goiás: Colinas do Sul, Serra da Mesa, -14.0166, -49.02, 2 Dec 1995, B. H. Dietz, Campaner; Faz. Pau Brasil, nr. Jussara, -15.5835, -51.3966 ± 6m, 305m, 30 Sep 2008, J. Sosa-Calvo, T. R. Schultz; Maranhão: Bom Jardim, REBIO Gurupi Parcela 01 08, -3.9258, -46.7712, 20 Sep 2014, A. Y. Harada; Centro Novo Maranhão, REBIO Gurupi, Parcela 02, -3.682111, -46.7798, 18 Jul 2014, A. Y. Harada; Minas Gerais: Uberlândia, Panga, -19.18314, -48.40141, 813m, 18 Oct 2012, A. Ješovnik; Uberlândia, Panga, -19.10557, -48.23849, 810m, 22 Sep 2008, J. Sosa-Calvo; Uberlândia, Panga, -19.1666, -48.3833, 790m, 22 Sep 2008, T. R. Schultz; Viçosa, -20.7833, -42.8333, 30 Oct 2014, R. Jesus, J. Chaul; Pará: Belém, IPEAN APEG, [-1.4373, -48.4706], 19 Jul 1971, I. B. de Almeida; Belém, Parque R.A., [-1.4585, -48.4372], R.C.G.; Belém, Utinga Forest Preserve, -1.4174, -48.4288 ± 5m, 45m, 3 Feb 2009, J. Sosa-Calvo; Marituba, CEPLAC Station, [-1.3666, -48.3333], 16 Oct 2004, J. R. M. Santos; Melgaço, Caxiuanã, ECFPn, -1.7248, -51.4230, 20 Oct 2007, A. Y. Harada; Nova Ipixuna, Fazenda Bom Retiro, Parcela 02, -4.8412, -49.218, 12 Apr 2012, M. Tavares, A. Palmeira; Parauapebas, FL Nacional de Carajás, Parque Zoobotânico, -6.06292, -50.05712, 626m, 3 Oct 2014, A. Ješovnik; Tailândia, Fazenda Santa Marta, Juruá Florestal, [-3.0167, -64.2667], 28 May 2002; Rondônia: Ilha do Bufalo, km 0.5, subparcela 250, -9.0818, -64.2125, 90m, 26 Oct 2013, I. O. Fernandes; Ilha Pedras, km 4, subparcela 100, -9.1512, -64.578, 86m, 25 Oct 2013, I. O. Fernandes; Jaci-Paraná, km 4, subparcela 150, -9.2656, -64.2125, 94m, 26 Nov 2011, I. O. Fernandes; Rio Jamari, São Pedro, [-10.2, -63.25], 11 Jun 1960, OP Fora Hini; São Paulo: Cananéia, Ilha do Cardoso, -28.0968, -47.9298, 24 Dec 2002, R. R. Silva, C. R. F. Brandão, C. Scott; Faz. Itaquerê, Nova Europa, [-21.7838, -48.5578], 2 Dec 1963, K. Lenko; Jacupiranga, [-24.7055, -48.0167], 1 Nov 1963, F. Plaumann; Jureia-Itantins, -24.5442, -47.235; Sergipe: Areia Branca, PN Serra de Itabaiana, -10.765, -37.3326, 19 May 2003, R. R. Silva, B. H. Dietz, L. S. Ferreira; Tocantins: Araguacema, -8.9886, -49.6675, 16 Nov 2005, R. R. Silva, R. M. Feitosa; Goiatins, -7.9793, -47.2507, 3 May 2005, R. R. Silva, B. H. Dietz; Paraná, Serra da Contenda, -13.3576, -47.6756, 13 Oct 2004, R. R. Silva, B. H. Dietz; Porto Nacional, Faz. Alto Paraíso, Transecto 1, -10.7089, -48.4680, 30 Sep 2001, R. R. Silva, N. L. Albuquerque; COLOMBIA: Amazonas: PNN Amacayacu Matamata, -3.6833, -70.25, 150m, 17 Jan 2001, A. Alvarado; Caquetá: Puerto Solano, PNN Serranía de Chiribiquete, Río Cuñaré, 0.5, -72.631, 250m, 1 Nov 2000, E. Gonzales; ECUADOR: Manabi: 73km NE Chone, B364, [-0.363, -79.739 ± 10000m], 300m, 12 Jun 1976, S., J. Peck; Orellana: Tiputini Biodiversity Station, -0.6333, -76.1333, 10 Feb 2003, K. T. Ryder Wilkie; Sucumbíos: Reserva Faunistico Cuyabeno, 0.1167, -76.1833, 1 Nov 1994, J. P. Caldwell; FRENCH GUIANA: Cayenne: Régina, Nouragues Field Station, intersect. trails 16&L, 4.0849, -52.6771, 95m, 4 Aug 2005, T. R. Schultz; GUYANA: Cuyuni-Mazaruni: Calm Water Creek, along Essequibo River, nr. Bartica, 6.466667, -58.65, 26 Sep 2002, J. S. La Polla; PERU: Huánuco: Monson Valley, Tingo Maria, -9.3167, -76.0167, 600m, 10 Nov 1954, E. I. Schlinger, E. S. Ross; Madre de Dios: Tambopata Reserve, -12.8187, -69.3636, 224m, 1 Aug 2012, A. Ješovnik; SURINAME: Sipaliwini: Lely Mountains, 4.2529, -54.7561, 619m, 26 Oct 2005, J. Sosa-Calvo, R. Badal; Nassau Mountains, 4.8172, -54.6067, 514m, 3 Nov 2005, J. Sosa-Calvo.