Willowsia neonigromaculata, Cipola & Katz, 2021

Cipola, Nikolas G. & Katz, Aron D., 2021, Morphological and molecular analysis of Willowsia nigromaculata (Collembola, Entomobryidae, Entomobryinae) reveals a new cryptic species from the United States, European Journal of Taxonomy 739 (1), pp. 92-116 : 104-108

Willowsia neonigromaculata sp. nov. Katz & Cipola

urn:lsid:zoobank.org:act:195E3CC7-B9AB-4CE9-93DE-BBA8ABA443C9

Figs 8–11 ; Tables 2–3

Willowsia nigromaculata – Katz 2015a: 829, Illinois, USA (phylogeny). — Katz 2015b: 64, Illinois, USA (phylogeny). — Katz 2017: 553 , Illinois, USA (descr.). — deWaard et al. 2019: suppl. data, Brockville, Canada (DNA barcode, GenBank MG034057 ).

Diagnosis

Body with pigments laterally on head to Abd III, and spots on Abd IV, femur and tibiotarsus ( Fig. 8 ), sometimes with piment covering nearly all Abd II–III medially and posterior half of Abd IV; head mac S0 present or absent, Ps3 mes and Ps5 mac absent ( Fig. 9A ); sublobal plate with 3 inner appendages ( Fig. 9B ); Th II–Abd IV formula with 9,8|3,3,3+7,7+14 mac, p2a present on Th III; manubrium dorsally with 9 lateral chaetae abruptly acuminate at the tip, manubrial plate with 4 chaetae, 2 mac ( Fig. 9E ).

Etymology

The specific epithet is derived from the Greek adjective ‘νέος, -α, -ον’, Latinized ‘ neos, - a, - um ’ (combining form neo -), ‘new, recent, young’ + the epithet of the species Willowsia nigromaculata

( Lubbock, 1873). The name references the new species’ morphological affinity with W. nigromaculata and its presence in the New World.

Material examined

Holotype USA • 1 ♀ on slide; Illinois, Pope Co., Dixon Springs Agricultural Center ; 37°26′03.65″ N, 88°40′01.84″ W; altitude 524 m, hand collected on pavement on dying Arilus cristatus ; 23 Sep. 2011; A. Katz leg.; adk11-159; INHS 810161 .

Paratypes USA • 1 ♂, 2 ♀, 2 undetermined sex on slides and 30 specimens in alcohol; same data as for holotype; INHS 810157–810160 , INHS 810162 , INHS 810163 .

Other material

USA • 1 undetermined sex on slide; Illinois, Urbana, 19 Montclair Rd ; 40°05′41.5″ N, 88°12′24.7″ W; 6 Jul. 2008; by kitchen sink; F Soto-Adames leg.; INHS 810,164 • 2 ♀♀ on slide; same collection data as for preceding, except 2012 (no specific date); INHS 810165 .

Description

LENGTH. Total length (head + trunk) of specimens 1.51–1.85 mm (n = 3). Specimens pale yellowish white with violet pigments on distal half of the Ant I to Ant IV, head laterally, margins of Th II–Abd II, Abd III with one transverse band that expands laterally, Abd IV dorsally with one irregular lateral spot and one weak central spot, irregular spots on dorsoventral plate and posterior margin; distal half of Abd V to VI, distal femur and tibiotarsus medially; eyepatches black ( Fig. 8 ). Sometimes depigmented on proximal part of the Ant II; pigments on posterior one third of the Th II and Abd I, almost all Abd II–III medially, and posterior half of Abd IV (see Katz 2017: 551).

HEAD. Antennal ratio as I: II: III: IV = 1: 1.83–2.00: 1.68–2.12: 1.81–2.36 (n = 3). Ant IV not annulated, with apical bulb simple or bilobed, rarely retracted. Six interocular chaetae (q, v, s, p, r, t); head dorsal macrochaetotaxy ( Fig. 9A ) with 5 ‘An’ (An1a–3), 4 ‘A’ (A0, A2–3, A5), 3 ‘M’ (M1–2, M4), 6–7 ‘S’ (S0, S2–6), 0 ‘Ps’, 5 ‘Pa’ (Pa1–5), 2 ‘Pm’ (Pm1, Pm3), 4 ‘Pp’ (Pp1–3, Pp5), and 4 ‘Pe’ (Pe2–3 plus 1 unnamed) mac; An2a?, A1, A4? mic absent. Maxillary palp with t.a. smooth and b.c. weakly striated, thicker and 1.10 longer than t.a.; sublobal plate with 3 inner (sb.1–3) and 1 outer (sb.4) smooth appendages, sb.1 gently smaller, sb.3 thin, and sb.4 minute ( Fig. 9B ). Ventral chaetotaxy with about 74 ciliate chaetae, 23 thin, 18 slightly smaller, and 33 normal and subequal in length (including b.c.), cephalic groove with 8 chaetae; postlabial formula with 4 (G1–4), 4 (X, X2–4), 4 (H2–4), 4 (J1–4), 2 (X’, X4’) chaetae ( Fig. 9C ).

THORAX CHAETOTAXY (as Fig. 6A ). Th II and III similar to W. nigromaculata , except Th III p2a mac always present. Ratio Th II: III = 1.48–1.30: 1 (n = 3), holotype 1.30: 1.

ABDOMEN CHAETOTAXY (as Figs 6B–F and 9D ). Abd I to IV similar to W. nigromaculata , except Abd I m2 smaller in length and socket size, Abd II a5 and m2 bothriotricha with 8–9 and 6 accessory chaetae, Abd III m2 bothriotrichum with 3–4 accessory chaetae and a5 and m5 bothriotricha with 12–15 accessory chaetae between them, and Abd IV T2 and T4 bothriotricha with 2 mic and 8–11 accessory chaetae between them. Abd V a, m and p series with 1 (a5), 4 (m2–3, m5–5e), and 5 (p1, p3–6) mac, respectively ( Fig. 9D ). Ratio Abd III: IV = 1: 3.61–4.14 (n= 3), holotype 1: 3.80.

CHAETOTAXY OF THE LEGS AND COLLOPHORE. Similar to W. nigromaculata ( Fig. 7A–F ).

FURCULA. Manubrium ventrally similar to W. nigromaculata (as Figs 4C , 7I ); dorsally with one lateral row of 9 ciliate chaetae abruptly acuminate at the tip, 3 mac and 6 mes (2 basal and 2 antero-subapical); manubrial plate with 4 ciliate chaetae of different sizes (2 mac abruptly acuminate at the tip) and 2 psp ( Fig. 9E ).

DNA Barcodes

GenBank KM610130 ; collection locality information same as holotype ( Katz et al. 2015a). GenBank MG034057 ; Brockville, Canada ( deWaard et al. 2019).

Remarks

Willowsia neonigromaculata sp. nov. is considered a new species that is distinct from W. nigromaculata , supported by both morphological ( Table 2 ) and molecular evidence ( Table 3 , Figs 10–11 ). Willowsia neonigromaculata sp. nov. resembles W. nigromaculata in most morphological characteristics, but differs in head by cephalic mac Ps5 and Pp4 absent and Pe4 plus one extra mac present (opposite in W. nigromaculata ), 3 mic (An2a?, A1, A4?) absent (present in W. nigromaculata ) and interocular s chaetae present (absent in W. nigromaculata ), sublobal plate with 3 inner appendages (2 in W. nigromaculata ), and ventral groove with 8 chaetae (6 in W. nigromaculata ). On Abd I, m2 mac for Willowsia neonigromaculata sp. nov. smaller in length and socket size than m3 and m4 (normal in W. nigromaculata ), and Abd V with 3 chaetae (m5ea, p5a, p6e), all absent in W. nigromaculata . They also differ in manubrium dorsally with 2 basal and 2 antero-subapical chaetae abruptly acuminate at the tip (1 basal and 1 antero-subapical in W. nigromaculata ), and manubrial plate with 2 inner mac (1 in W. nigromaculata ).

Figures

Fig. 8. Willowsia neonigromaculata sp. nov., paratype, ♀ (INHS 810158), habitus. A. Lateral view. B. Dorsal view. Scale bars: 0.5 mm.

Fig. 9. Willowsia neonigromaculata sp. nov., body parts (left side). A. Cephalic dorsal chaetotaxy. B. Maxillary outer lobe. C. Complete postlabial chaetotaxy. D. Abd V dorsal chaetotaxy. E. Manubrium dorsal chaetotaxy. Abbreviations: see Material and methods.

Fig. 10. COI p-distance (uncorrected) frequency histogram (in gray) and boxplots comparing p-distances between A. Entomobryinae species. B. Entomobryinae sister species. C. Willowsia nigromaculata (Lubbock, 1873) (France and Toronto, Canada) and W. neonigromaculata sp. nov (USA and Brockville, Canada) clades (inter-specific distances). D. Lineages within the same W. nigromaculata or W. neonigromaculata sp. nov. clade (intra-specific distances).

Fig.11.BayesianconsensustreeestimatedwithMrBayesforEntomobryinae,includingthecladecomprised of Willowsia nigromaculata (Lubbock, 1873) from France and Canada and W. neonigromaculata sp. nov. from the USA and Canada (highlighted). MrBayes and BEAST posterior probabilities and RAxML bootstraps are indicated at each node, respectively. The ingroup node constrained as monophyletic for all phylogenetic analyses is indicated with an asterisk (*).

Fig. 6. Willowsia nigromaculata (Lubbock, 1873), dorsal chaetotaxy (left side). A. Th II–III. B. Abd I–III. C. Abd IV–V. D–F. Bothriotrichal complex. D. Abd II. E. Abd III. F. Abd IV. Abbreviations: see Material and methods.

Fig. 7. Willowsia nigromaculata (Lubbock, 1873). A. Subcoxa I. B. Subcoxa II. C. Subcoxa III (lateral view). D. Trochanteral organ. E. Distal tibiotarsus and empodial complex III (posterior view). F. Collophore chaetotaxy (lateral view). G. Manubrium dorsal chaetotaxy. H. Manubrial plate. I. Subapical and apical chaetotaxy of ventral manubrium. J. Mucro (lateral view). Abbreviations: see Material and methods.

Fig. 4.Optical microscope photography of Willowsia nigromaculata(Lubbock, 1873). A. Furcula (dorsal view). B. Manubrium (dorsal view), arrows indicate mac and mes suddenly acuminate, respectively. C. Manubrium and proximal dentes (ventral view), arrow indicate subapical chaetae. Scale bars: A, C =100 μm; B = 50 μm.