Pseudosinella vulcana Katz, Soto-Adames & Taylor

Katz, Aron D., Taylor, Steven J., Soto-Adames, Felipe N., Addison, Aaron, Hoese, Geoffrey B., Sutton, Michael R. & Toulkeridis, Theofilos, 2016, New records and new species of springtails (Collembola: Entomobryidae, Paronellidae) from lava tubes of the Galapagos Islands (Ecuador), Subterranean Biology 17, pp. 77-120 : 94-97

Taxon classification Animalia Collembola Entomobryidae

Pseudosinella vulcana Katz, Soto-Adames & Taylor sp. n. Figs 18, 19, 20

Etymology.

Latin, feminine form, alludes to the shield volcanoes of the Galápagos Islands.

Type material.

Holotype, ♂ on slide, Ecuador, Galápagos, Santa Cruz Island: Cueva Chato 2, leaf litter at entrance, 15.iii.2014 (S. Taylor, J. Jacoby, S. Hagan and R. Toomey), GLP-086, INHS Acc. 567,411.

Paratypes, Ecuador, Galápagos, Santa Cruz Island: 1♀ on slide, Cueva Chato 2, leaf litter at entrance, 15.iii.2014 (S. Taylor, J. Jacoby, S. Hagan and R Toomey), GLP-086, INHS Acc. 567,412; 1♀ on slide, Cueva Chato 2, drip pool, dark zone, 15.iii.2014 (S. Taylor, J. Jacoby, S. Hagan and R. Toomey), GLP-090, INHS Acc. 567,413; 1♀ on slide, Cueva Chato 2, drip pool, dark zone, 15.iii.2014 (S. Taylor, J. Jacoby, S. Hagan and R. Toomey), GLP-090, CDRS.

Description.

Body shape and color pattern. Maximum body length 0.74mm (♀) and 0.68mm (♂). Body white, without pigment, except for minute black eye spot (Fig. 18A).

Appendicular scales distribution. Scales limited to head, body and ventral face of furcula. Antennae, legs, ventral tube and dorsal face of furcula without scales.

Head. Apical bulb of Ant. IV absent; subapical sense organ clubbed, as large as guard sensillum; additional bulb-like sense organ present within a deep pit. Sense organ of Ant. III with 2 normal rods; at least 2 additional short, blunt sensilla present. Eyes 1+1, each within a minute eye spot. Dorsal head chaetotaxy (Fig. 18B) with 5+5 Mc in An series, in addition to Mc A0, A2, A3, and Pa5. Prelabral setae acuminate and weakly ciliate. Proximal labral setae ciliate, medial and distal labral setae smooth. Distal margin of labrum smooth. Outer maxillary lobe with basal and distal setae smooth and subequal; sublobal plate with 3 seta-like appendages, middle appendage 2' longer and 2' thicker than outer appendage. Lateral appendage of labial papilla E S-shaped, not reaching tip of papilla. Proximal labial setae smooth. Labial triangle setae formula: M1rEL1L2A1-5; A1-5 smooth; r minute, smooth, and conical; all other posterior setae ciliate (Fig. 18C). Postlabial setae ciliate; 3 setae and 4 scales along each side of ventral groove; modified setae absent.

Dorsal body chaetotaxy. Th. II without Mc (Fig. 19A): polychaetosis absent; mesothoracic hood not developed. Th. III without Mc (Fig. 19B). Abd. I (Fig. 19C) with 9 posterior mc; seta a6 absent. Abd. II (Fig. 19D) with 3 Mc (m3, m5, a2); Mc a2 short, thickened distally, with relatively small socket; supplementary setae mi, Li, Ll and m4i associated with bothriotricha m2 and a5 ciliate and weakly fan-shaped/truncate; all other mc acuminate and smooth; mc a2p and Lm, absent; seta a3 external to and half the length of as. Abd. III (Fig. 20A) with 2 Mc (pm6, p6); supplementary mc mi, ml, a2, Li, Lm, im and a6 weakly fan-shaped and ciliate, all other mc smooth; sensillum d2 and mc c3 and Ll absent; seta a3 anterior to and nearly reaching sensillum as; as twice as long as m3; seta a7 posterior to im and em and external to am6. Abd. IV (Fig. 20B) with 2 inner (B5, C1) and 4 lateral Mc (D3, E2, E3, F1); at least 1 additional posterior-lateral Mc of uncertain homology present; supplementary mc associated with bothriotricha weakly fan-shaped and ciliate; seta s present; mc T3 anterior to and not reaching D1p; posterior setae absent.

Legs. Trochanteral organ with up to 9 setae. Metatibiotarsi with 2 outstanding posterior blunt seta. Tenent hair short and acuminate. Unguis with 4 inner teeth; 1 large wing-like inner tooth with 2 basal minute paired lateral teeth, and 1 unpaired proximal tooth. Unguiculus basally swollen on all legs; with 1 large outer wing tooth (Fig. 20C).

Ventral tube. Lateral flaps with 4+4 or 5+5 smooth setae, anterior face with 4+4 ciliate setae, and posterior face (Fig. 20D) with 1+1 smooth setae and 1+1 minute conic microsensilla.

Furcula. Dens tubercle absent. Mucro with sub-apical tooth larger than apical tooth; basal spine smooth.

Remarks.

Pseudosinella vulcana sp. n. is the only member of the genus with 1+1 eyes and with a wing tooth on both the unguis and unguiculus. This new species is most similar to Pseudosinella biunguiculata Ellis, 1967, sensu Mari Mutt (1986), but differs by having 1+1 eyes, Abd. IV supplemental seta s present (Fig. 20B), and only 1+1 paired setae on the posterior face of the collophore (Fig. 20D), where as in Pseudosinella biunguiculata eyes and supplemental seta s are absent and the posterior face of the collophore has 2+2 paired setae and 1 unpaired medial seta.

Pseudosinella vulcana sp. n. has 2 thickened, apically blunt metatibiotarsal setae, which was originally thought to differ from Pseudosinella biunguiculata since Mari Mutt (1986) described only 1 blunt metatibiotarsal seta. However, we observed 2 metatibiotarsal setae on Pseudosinella biunguiculata from Puerto Rico (Guajataca Commonwealth Forest, at end of trail #10, leaf litter, 19.v.2009, F. Soto, coll.). Pseudosinella caoi Chen, Wang & Christiansen, 2002 and Pseudosinella fujiokai Yosii, 1964, sensu Christiansen and Bellinger (1992), also have blunt metatibiotarsal setae, ungual wing teeth, Head Mc A3 (R2), and lack Mc on Th. II and Th. III, but can be differentiated from Pseudosinella vulcana sp. n. by characters outlined in Table 2.

Mari Mutt (1986) described 3 morphologically distinct forms among and within populations of Pseudosinella biunguiculata in Puerto Rico that differ in dorsal chaetotaxy (presence/absence of head Mc A3 (R2)) and tenent hair morphology (clavate/acuminate). He also noted differences between the Puerto Rican forms and Ellis’ (1967) type specimens; primarily the absence of head Mc A2 (R1), A3 (R2), and Pa5 (Po) on the holotype. Furthermore, the original description of Pseudosinella biunguiculata does not show the presence of m4i on Abd. II, which is distinctly present in the Puerto Rico populations. The high levels of morphological variation exhibited among these forms suggest that Pseudosinella biunguiculata represents a species complex: small and seemingly insignificant differences in morphology have been shown to correlate with large genetic distances among populations, indicating the presence of species complexes ( Porco et al. 2012, Cicconardi et al. 2013, Katz et al. 2015a). In fact, Soto-Adames (2002b) observed large genetic differences between sympatric individuals of Puerto Rican Pseudosinella biunguiculata , but these differences could not be correlated with differences in morphology due to destructive DNA extraction methods. Additional investigations utilizing morphological and molecular data may clarify species-level relationships among populations of Pseudosinella biunguiculata , a species with a widespread neotropical distribution. See Table 2 for a list of diagnostic characters separating the different forms and descriptions of Pseudosinella biunguiculata .

Pseudosinella vulcana sp. n. was collected from entrance and from the surface of a drip pool (Fig. 2A) within the dark zone, in generally cool, moist, low light conditions (Table 3), suggesting the species may be a troglophile.

Distribution.

Santa Cruz Island, Galápagos, Ecuador.