Nylanderia deyrupi, Messer & Cover & Rabeling, 2020

Messer, Steven J., Cover, Stefan P. & Rabeling, Christian, 2020, Two new species of socially parasitic Nylanderia ants from the southeastern United States, ZooKeys 921, pp. 23-48 : 23

Nylanderia deyrupi sp. nov. Figures 2A, C, E (queen), 3A, C, E (male); see Plate 88 in Deyrup (2016): p. 348.

Material examined.

Holotype: USA • alate queen; Florida, Highlands Co., Archbold Biological Station; 27.187N, 81.335W, elevation above sea level: 61 m; scrubby flatwoods, slash pine, Quercus inopina , Q. geminata , Palmetto, Lyonia lucida : under leaf-litter of oak canopy at edge gap in pure sand; 15-September-1995; Stefan P. Cover leg.; MCZ-ENT00716681. Deposited at MCZC.

Paratypes: USA • 1 alate queen; same data as for holotype; MCZ-ENT00716678 • 1 male; same data as for holotype; MCZ-ENT00716681 • 1 alate queen, 1 male (on same pin); same data as for holotype; MCZ-ENT00716684 • 1 alate queen, 1 male (on same pin); same data as for holotype; MCZ-ENT00716690 • 1 male; same data as for holotype; MCZ-ENT00716693 • 1 male; same data as for holotype; MCZ-ENT00716694. MCZ-ENT00716678, MCZ-ENT00716681, MCZ-ENT00716693, MCZ-ENT00716694 deposited at the MCZC; MCZ-ENT00716684, MCZ-ENT00716690 deposited at SIBR.

USA • 1 alate queen; Florida, Highlands Co., Archbold Biological Station; 27.187N, 81.335W, elevation above sea level: 61 m; malaise trap; 6-X-1983; Mark Deyrup leg.; ASUSIBR00000365 • 1 alate queen; same data as previous; but 8-X-1983; ASUSIBR00000366 • 1 alate queen; same data as previous; but 20-X-1983 ASUSIBR00000367 • 2 alate queens; same data as previous; but 26-X-1983; ASUSIBR00000368-369 • 3 alate queens; same data as previous; but 30-X-1983; ASUSIBR00000370-372 • 2 alate queens; same data as previous; but 15-XI-1983; ASUSIBR00000373-374 • 1 alate queen; same data as previous; but 19-XI-1983; ASUSIBR00000375 • 2 alate queens; same data as previous; but 23-IX-1985; ASUSIBR00000376-377 • 1 alate queen; same data as previous; but 4-X-1985; ASUSIBR00000378 • 1 alate queen; same data as previous; but 9-X-1985; ASUSIBR00000379 • 1 alate queen; same data as previous; but 12-X-1985; ASUSIBR00000380 • 1 alate queen; same data as previous; but 25-XI-1986; ASUSIBR00000381. ASUSIBR00000365-368, ASUSIBR000370-371, ASUSIBR00000373, ASUSIBR00000375-376, ASUSIBR00000378-381 deposited at MCZC; ASUSIBR00000369, ASUSIBR00000372, ASUSIBR00000374, ASUSIBR00000377 deposited at SIBR.

USA • 3 alate queens; Florida, Highlands Co., Archbold Biological Station; 27.187N, 81.335W; 25-Sept-2010; John LaPolla leg.; JSL100925-1/ASUSIBR00000382-384 • 1 alate queen; same data as previous; JSL100925-2/ASUSIBR00000385 • 1 alate queen; same data as previous; JSL100925-3/ASUSIBR00000386 • 3 alate queens; same data as previous; JSL100925-4/ASUSIBR00000387-389. ASUSIBR00000382, ASUSIBR00000389 deposited at MCZC; ASUSIBR00000383, ASUSIBR00000388 deposited at USMN; ASUSIBR00000384-387 deposited at SIBR.

Diagnosis.

A workerless inquiline characterized by small alate queens and apterous males. Queens are easily distinguished from host queens by their smaller size (WL: N. deyrupi = 0.79-0.90 vs. N. wojciki = 1.10-1.16; Fig. 6 ), uniformly lighter coloration, long antennal scapes (SI = 118-130 vs. 86-101 in the host), reduced CI (86-94 vs. 95-97 in the host), reduced mandibular dentition (mandible = 3-4 teeth, host = 6 teeth), and reduced macrosetae counts on antennal scapes (2-6 vs. 1-2). In addition, the eyes exceed the lateral margins of the head and hind wing venation is slightly reduced. Males of N. deyrupi are completely apterous and are bicolored with a darker head and gaster and lighter mesosoma. The mesonotum is also reduced and narrow from the reduction of flight musculature and does not protrude anteriorly beyond the pronotum. Host males are fully alate and uniform brown. The antennal scapes lack macrosetae. Reduced REL (27-28 vs. 35-40) and SI increased (112-121 vs. 104-107).

Queens of Nylanderia deyrupi differ from those of the closely similar N. deceptrix by their smaller overall size (WL: N. deyrupi = 0.79-0.90 vs. N. deceptrix = 0.99-1.07; Fig. 7 ), reduced number of macrosetae on the mesonotum (10-17 vs. 21-27), smaller eyes (REL 24-31 vs. 33-37), and uniform coloration (queens of N. deceptrix are bicolored). Nylanderia deyrupi males are smaller in size (WL 0.55-0.58 vs. 0.66-0.69), possess more macrosetae on the mesonotum (4-5 vs. 2), pronotal macrosetae are absent, smaller eyes (REL 27-28 vs. 34-36), and shorter antennal scapes (SI 112-121 vs. 125-127).

Description, holotype gyne.

Measurements: TL 2.68, HW 0.56, HL 0.59, EL 0.17, SL 0.65, MW 0.47, PW 0.57, WL 0.85, GL 1.23, PDH 0.32, PFL 0.69, PFW 0.15, SMC 4, PMC 3, MMC 14, MtMC 3. Indices: CI 94, REL 29, SI 118, FI 21. Small size (TL 2.68), body yellow-brown in color, dorsum of head and gaster slightly darker. Head: covered in pubescence and macrosetae, slightly longer than wide (CI 94), broadening posteriorly, eyes protruding beyond lateral margins of head, three ocelli present. Maxillary and labial palp formula 6:4, mandibular dentition reduced to apical and three pre-apical teeth. Antennal scapes long (SI 118), exceeding posterior margin of head by length of first three funicular segments, covered in appressed setae with four erect macrosetae. Antennae 12-segmented. Mesosoma: dorsum covered with pubescence, largely absent on lateral portions of mesosoma, pronotum bearing three macrosetae, mesonotum bearing 14 macrosetae, metanotum bearing three macrosetae, macrosetae matching body color, macrosetae on metanotum displaying significant curvature towards midline of body. Forewings smaller in size, but not distinctly different from forewings of host, hindwings with slightly reduced venation relative to host. Metasoma: gaster covered in pubescence with clusters of macrosetae at anterior portion of first gastric tergite and posteriorly around acidopore.

Measurements, paratype gynes

(N = 28): TL 2.35-2.88, HW 0.51-0.56, HL 0.58-0.62, EL 0.15- 0.19, SL 0.64-0.67, MW 0.42-0.54, PW 0.42-0.62, WL 0.79-0.90, GL 0.96-1.38, PDH 0.30-0.35, PFL 0.55-0.72, PFW 0.09-0.15, SMC 2-6, PMC 2-6, MMC 10-17, MtMC 2-4. Indices: CI 86-94, REL 24-31, SI 118-130, FI 16-24.

Description, paratype males.

Measurements (N = 5): TL 1.80-1.84, HW 0.41-0.42, HL 0.44-0.46, EL 0.12-0.13, SL 0.46-0.50, MW 0.22-0.25, PW 0.28-0.31, WL 0.55-0.58, GL 0.78-0.83, PDH 0.21-0.23, PFL 0.48-0.51, PFW 0.10-0.11, PL 0.20-0.21, SMC 0, PMC 0, MMC 4-5, MtMC 1-2. Indices: CI 90-93, REL 27-28, SI 112-121, FI 20-23. Overall yellowish-brown, exhibiting bicoloration with head and gaster darker than mesosoma, yellow color in legs, antennae and mandibles, macrosetae color matching body segment. Head: slightly longer than wide (CI 90-93), covered in pubescence and macrosetae, denser posteriorly and laterally, eyes protruding beyond lateral margins of head, three ocelli present. Maxillary and labial palp formula 6:4, mandibular dentition reduced to apical tooth only. Antennal scapes long (SI 112-121), exceeding posterior margin of head by length of funicular segments I-III, covered in pubescence and lacking erect macrosetae. Antennae 13-segmented. Mesosoma: small, completely apterous, largely lacking any pubescence. Pronotum lacking macrosetae, mesonotum offset posteriorly from pronotum and rising abruptly possessing four or five macrosetae, metanotum bearing one or two macrosetae that curve towards midline of body. Legs lacking macrosetae. Metasoma: petiole triangular with longer posterior face sparsely covered in pubescence, macrosetae present on anterior of first gastral tergite and posterior margins of tergites and sternites. Genitalia: parameres narrowly triangular, densely covered in macrosetae, slight mesad curvature at posterior end, digiti narrow and tubular, cuspi broad anteriorly and narrow laterally at posterior end.

Etymology.

This species is named in honor of Mark Deyrup, who first discovered the miniature females of N. deyrupi in malaise trap samples. Mark Deyrup has been a resident naturalist at Archbold Biological Research Station in Central Florida since 1982, and he is a uniquely gifted natural historian who acquired a phenomenal knowledge about the biology of the ants of Florida. Mark recently synthesized his knowledge in the richly illustrated monograph on the Ants of Florida ( Deyrup 2016). His meticulous studies of ant natural history and taxonomy have inspired students and colleagues alike for decades, and without Mark’s insightful studies the rich natural history of Florida would be much less explored.

Distribution and natural history.

Nylanderia deyrupi is a rare, apparently workerless inquiline social parasite occurring only in nests of its host, Nylanderia wojciki . It is similar in morphology, and apparently in life-history, to Nylanderia deceptrix , the inquiline parasite of N. parvula . Its host, N. wojciki is native to Florida and the adjacent southeastern states. It is a common ant in sandhill and pine flatwood communities. In contrast, N. deyrupi is presently known only from Archbold Biological Station and two areas east of Sebring in Highlands County, Florida (Fig. 9 ; see also Deyrup 2016), all of which are located on the Lake Wales Ridge in central Florida. This sand ridge is more than one million years old ( Turner et al. 2006), and it is home to endemic plants and animals, all narrowly distributed on the ridge itself. Deyrup (2016) suggested that N. deyrupi (referred to as Nylanderia Species A in Deyrup 2016) may be another such endemic species.

The host, N. wojciki , makes small (<300 workers), usually monogynous colonies nesting in leaf litter or sand, usually in partly or lightly shaded areas ( Trager 1984). The nests are often diffuse in the summer months, consisting of multiple shallow chambers within an area of 1-2 square meters, containing workers, brood, and sometimes sexuals. Collections of N. deyrupi consisted of queens and males scattered among these small host nest pockets, a pattern extremely similar to that seen in N. deceptrix and its host N. parvula . A striking feature of its life history, also shared with N. deceptrix , is that, unlike many ant inquilines, N. deyrupi does not appear to suppress the development of host sexuals. In collections made by M. Deyrup and S. Cover both host and parasite sexuals were commonly found together in the host nest, along with host worker brood and callows, strongly suggesting that the host queen is retained, not eliminated in parasitized colonies, coexisting with the social parasite. Another interesting life-history trait shared with N. deceptrix is the production of apterous males, which is unique among Nylanderia ants. Accordingly, males have limited mobility and probably no dispersal capability, and mating is expected to occur in or around the host nest (i.e., adelphogamy). Considering the limited mobility and the small number of males present in each nest, inbreeding is expected to occur in N. deyrupi . In addition, N. deyrupi has a strongly female-biased sex ratio, a phenomenon that has been frequently observed among inquiline social parasites.

Worker caste.

Nylanderia deyrupi was repeatedly collected from nests of N. wojciki and workers of N. deyrupi were never encountered. Thus, it is likely that N. deyrupi is a workerless inquiline social parasite.

Figures

Figure 2. Gynes of the social parasite Nylanderia deyrupi (A, C, E) and its host Nylanderia wojciki (B, D, F) in full-face (A, B), lateral (C, D), and dorsal (E, F) views. Scale bars: 0.1 mm (A, B), 0.5 mm (C-F).

Figure 6. Boxplots comparing body sizes (Weber's Length) of social parasite queens (red) to the queens (light blue) and workers (dark blue) of their respective host species. Letters above the boxes indicate significantly different groups (Pairwise Mann-Whitney Test with Bonferroni correction, P <0.05).

Figure 7. Boxplot comparing body sizes (Weber's Length) of social parasite queens to each other. Letters above the boxes indicate significantly different groups (Pairwise Mann-Whitney Test with Bonferroni correction, P <0.05).

Figure 9. Geographic distribution of N. deyrupi (black star) and its host N. wojciki (red circles). Host distribution data was supplemented with additional information from antmaps. org (Janicki et al. 2016).