Wangiannachiltonia guzikae, King, Rachael A., 2009

King, Rachael A., 2009, Two new genera and species of chiltoniid amphipods (Crustacea: Amphipoda: Talitroidea) from freshwater mound springs in South Australia, Zootaxa 2293, pp. 35-52 : 45-50

Wangiannachiltonia guzikae n. sp.

Figures 5–8

Material examined. Holotype, Male, SAM C6829, 2.9 mm, Davenport Springs, South Australia, 29° 39' 44.388"S 137° 35' 6.7914"E, Coll. M. Guzik and N. Murphy, 31 October 1997. Allotype, female, SAM C6830, 2.6 mm, collected with holotype. Paratypes, 3 males, 1 female, 1 juvenile, collected with holotype. Other material: SAM C6831, Davenport Springs, South Australia, 29° 40.09'S 137° 36.31'E, Coll. W. Zeidler and K. Gowlett-Holmes, 21 September 1989. SAM C6832, Welcome Springs, South Australia, 29° 40.75'S 137° 49.8'E, Coll. W. Zeidler and K. Gowlett-Holmes, 28 September 1989. SAM C6833, Old Finnis Springs, 29° 35.08'S 137° 27.0'E, Coll. W. Zeidler and K. Gowlett-Holmes, 21 September 1989. SAM C6834, Bopeechee Spring, South Australia, 29° 36.49'S 137° 23.15'E, Coll. W. Zeidler and K. Gowlett-Holmes, 1989. SAM C6835, Dead Boy Spring, South Australia, 29° 36.08'S 137° 24.44'E, Coll. W. Zeidler and K. Gowlett- Holmes, 22 September 1989. SAM C6836, West Finnis Springs, South Australia, 29° 35.68'S 137° 24.66'E, Coll. W. Zeidler and K. Gowlett-Holmes, 22 September 1989. SAM C6837, Elizabeth Springs, South Australia, 29° 21.36'S 136° 46.30'E, Coll. W. Zeidler and K. Gowlett-Holmes, 24 September 1989. SAM C6838, Beresford Spring, South Australia, 29° 16.0'S 136° 39.7'E, Coll. W. Zeidler and K. Gowlett-Holmes, 24 September 1989. SAM C6227, Coward Springs, South Australia, 29° 24.78'S 136° 47.28'E, Coll. W. Zeidler and K. Gowlett-Holmes, 23 September 1989.

Type Locality. Davenport Springs, South Australia.

Description. Holotype male. Length, 2.9 mm. Head (fig. 5A) about as long as deep. Antenna 1 (fig. 5B) peduncular article 1 twice as long as broad; peduncular article 2 about 0.75 times length of article 1, twice as long as broad; peduncular article 3 similar length to article 2, twice as long as broad; flagellum similar length to peduncle, of five articles, with one ventral aesthetasc on the proximal margin of the last two articles. Antenna 2 (fig. 5C) about 0.7 times length of antenna 1; peduncular article 1 broader than long; peduncular article 2 longer than article 1, slightly longer than broad; peduncular article 3 longer than article 2, twice as long as broad; flagellum similar length to peduncle, of five articles.

Upper lip (fig. 5G) slightly broader than long, apically bluntly rounded, with numerous short setae along apical margin. Lower lip (fig. 5H) with rounded lateral lobes, apical margins rounded, apical and inner margins with numerous short setae. Left mandible (fig. 5J) with incisor of five teeth, lacinia mobilis of four teeth, spine row of three plumose setae and triturative molar. Right mandible (fig. 5I) with incisor of six teeth, lacinia mobilis of three teeth, spine row of two plumose setae and triturative molar with a long plumose seta. Maxilla 1 (fig. 5F) outer plate with seven setulate robust setae; inner plate with two long apical plumose setae. Maxilla 2 (fig. 5E) outer plate with an apical row of 15 simple setae; inner plate with an apical row of 16 simple setae, with a plumose seta on the inner lateral margin below the apical row. Maxilliped (fig. 5D) inner plate apical margin with three short spine-like robust setae, with plumose seta along apical and inner lateral margins; outer plate with numerous simple setae along apical and inner lateral margins; palp articles 1 and 2 similar width, palp article 2 with numerous simple setae on inner lateral margin; palp article 3 not as broad as articles 1 and 2, with numerous simple setae on inner lateral and distal margins; palp article 4 short, about half as broad as article 3, with unguis and seta on distal margin.

Gnathopod 1 (fig. 6A) coxa distal margin with 14 short simple setae, ventral margin with two plumose setae at mid length; basis, ischium, and merus ventral margins with setae; carpus with ventral-lateral lobe and row of nine setulate setae becoming longer distally, dorsal-distal margin with long settulate setae, inner face with a single plumose seta; propodus triangular in shape, around 1.5 times as long as broad, ventral-distal corner with two robust seta (near where tip of dactylus touches), ventral-distal margin (adjacent to dactylus length) with long simple and short plumose setae, dorsal-distal margin with long simple setae, inner face with three robust plumose setae; dactylus curved, fitting just behind ventral-distal corner of propodus, with dorsal plumose seta. Gnathopod 2 (fig. 6B) coxa distal margin with nine short simple setae, ventral margin with three plumose setae at mid length; basis dorsal and ventral margins with setae; ischium and merus with scattered setae on ventral margins; carpus dorsal-distal margins with long settulate setae; propodus about as long as broad, without proximal lobe covering distal margin of carpus (see A. murphyi n. sp.), ventral-distal corner marked with a robust seta on each of the inner and outer faces, ventral-distal groove present on inner face to accommodate the tip of the dactylus, ventral distal margin with numerous apically bifid robust setae (not as robust as those marking the ventral distal corner). Pereopod 3 (fig. 6C) coxa distal margin with nine short simple setae; basis and ischium dorsal and ventral margins with setae; merus with strong dorsal-distal lobe, dorsal margin with plumose seta, dorsal-distal margin with long plumose setae, ventral-distal margin with long simple setae; carpus ventral margin with two apically bifid robust setae and scattered simple setae; propodus ventral margin with five apically bifid robust setae in four groups (distal seta smallest); dactylus dorsal margin with plumose seta, ventral margin with simple seta, unguis present. Pereopod 4 (fig. 6D) coxa with distinct proximal excavated corner, distal margin with 18 short simple setae; basis and ischium dorsal margins with setae; merus with strong dorsal-distal lobe, dorsal margin with long simple setae; carpus ventral margin with two apically bifid robust setae and scattered simple setae; propodus ventral margin with six apically bifid robust setae in four groups (distal seta smallest); dactylus dorsal margin with plumose seta, ventral margin with simple seta, unguis present. Pereopod 5 (fig. 6E) coxa ventral margin with six short simple setae; basis about as long as broad, dorsal margin with four apically divided robust setae along length, distal end of dorsal margin with two robust setae, ventral margin subtly crenulated and with eight short simple setae along length; ischium dorsal margin with distal robust setae; merus with strong postero-distal lobe, dorsal margin with robust setae in three clusters, ventral margin with robust setae in three clusters; carpus shorter than merus, dorsal margin with robust setae in two clusters, ventral margin with robust setae in one distal cluster; propodus similar length to merus, dorsal margin with five apically divided robust setae in four clusters (distal seta smallest), distal margin with long simple setae; dactylus with plumose seta on ventral margin, unguis present. Pereopod 6 (fig. 6F) coxa ventral margin with five short simple setae; basis slightly longer than broad, dorsal margin with five apically divided robust setae along length, distal end of dorsal margin with two robust setae, ventral margin subtly crenulated and with nine short simple setae along length; ischium dorsal margin with distal robust setae; merus with strong postero-distal lobe, dorsal margin with robust setae in three clusters, ventral margin with robust setae in three clusters; carpus shorter than merus, dorsal margin with robust setae in two clusters, ventral margin with robust setae in one distal cluster; propodus similar length to merus, dorsal margin with five apically divided robust setae in four clusters (distal seta smallest), distal margin with long simple setae; dactylus with plumose seta on ventral margin, unguis present. Pereopod 7 (fig. 6G) coxa margin with five short simple setae; basis about as long as broad, dorsal margin with four apically divided robust setae along length, distal end of dorsal margin with two robust setae, ventral margin subtly crenulated and with 14 short simple setae along length; ischium dorsal margin with distal robust setae; merus with strong postero-distal lobe, dorsal margin with robust setae in three clusters, ventral margin with robust setae in two clusters; carpus shorter than merus, dorsal margin with robust setae in three clusters, ventral margin with robust setae in one distal cluster; propodus similar length to merus, dorsal margin with seven apically divided robust setae in four clusters (distal seta smallest), distal margin with long simple setae; dactylus with plumose seta on ventral margin, unguis present.

Pleopods 1–3 similar, unmodified (as in Chiltonia ), peduncle inner margins with two distal retinacula (coupling hooks).

Uropod 1 (fig. 6H) peduncle distinctly longer than rami, dorsal margin with robust setae in three clusters along length; outer ramous distal margin with four robust setae of varying lengths; inner ramous with single seta at mid length, distal margin with five robust setae of varying lengths. Uropod 2 (fig. 6I) peduncle similar length to rami, dorsal margin with four long robust setae; outer ramous slightly smaller than inner ramous, distal margin with four robust setae of varying lengths; inner ramous with two robust setae at mid length, distal margin with five robust setae of varying lengths. Uropod 3 (fig. 6K) with one article, distal margin with one short robust seta and two long robust setae apically and one long seta subapically.

Telson (fig. 6J) slightly broader than long, apically blunt with robust setae at each distal corner.

Female. Length, 2.6 mm. Similar morphology to male except for the following.

Antenna 1 flagellum of four articles. Antenna 2 flagellum of four articles.

Gnathopod 1 (fig. 7A) coxa distal margin with seven short simple setae, ventral margin with one plumose seta at midlength; carpus with ventral-lateral lobe and row of six setulate setae becoming longer distally; propodus almost rectangular in shape, nearly two times as long as broad, ventral-distal corner with one robust seta (near where tip of dactylus touches), ventral-distal margin (adjacent to dactylus length) with long and short simple setae, dorsal-distal margin with long simple setae, inner face with one robust plumose seta; dactylus curved, fitting against ventral-distal corner of propodus, with dorsal plumose seta. Gnathopod 2 (fig. 7B) coxa distal margin with eight short simple setae; basis dorsal and ventral margins with setae; ischium and merus with setae on ventral margins; carpus with ventral-lateral lobe and row of six setulate setae becoming longer distally; propodus almost rectangular in shape, nearly two times as long as broad, ventral-distal corner with one robust seta (near where tip of dactylus touches), ventral-distal margin (adjacent to dactylus length) with long and short simple setae, dorsal-distal margin with long simple setae, inner face with one robust plumose seta; dactylus curved, fitting against ventral-distal corner of propodus, with dorsal plumose seta.

Uropod 3 (fig. 7C) distal margin with three long robust setae apically.

Oostegites present on coxae 2 to 5 (figs. 7D–G) to form the marsupium, margins with scattered curved hooks.

Etymology. Named for Dr Michelle Guzik (School of Earth and Environmental Sciences, The University of Adelaide), who collected many of the specimens studied for this examination.

Remarks. Wangiannachiltonia guzikae n. sp. is distributed throughout several springs in the southern Lake Eyre region and exhibits a high degree of subtle morphological variance. The flagellum of antenna 1 varied between five to six articles (in both sexes), antenna 2 flagellum varied between four to five articles (in both sexes), male gnathopod 2 propodus varied from short to distinctly longer than broad and the number of setae on the ventral distal margin varied between 9 to 19 (figs. 8A, D), uropod 1 peduncle setation varied from two to four (figs. 8B, E), uropod 2 peduncle usually had four robust setae but occasionally three or even five (figs. 8B, E), uropod 3 setation varied in the number of apical setae from three to five (figs. 8B, E). No clear groups could be distinguished based on these variable characters as often there were different combinations between individuals within spring populations. Size class differences and sexually dimorphic characters were accounted for. Overall, setation varied slightly with the size and sex of the animal. Females, which tended to be larger than males at maturity, had less setae on gnathopod and pereopod articles. Some males, as in a few from Old Finnis Springs (fig. 8C), possessed additional clusters of setae along the lengths of the pereopodal articles (usually more so in pereopod 7). Other mature males in the Old Finnis Springs sample were as illustrated for W. guzikae n. sp.

Figures

FIGURE 5. Wangiannachiltonia guzikae n. sp., holotype male, 2.9 mm. A, whole body, lateral view; B, antenna 1; C, antenna 2; D, maxilliped; E, maxilla 2; F, maxilla 1; G, upper lip; H, lower lip; I, right mandible; J, left mandible. Scales: 1 (A), 0.1 mm; 2 (B – C), 0.1 mm; 3 (D – J), 0.05 mm.

FIGURE 6. Wangiannachiltonia guzikae n. sp., holotype male, 2.9 mm. A, gnathopod 1 (with enlargement); B, gnathopod 2 (with enlargement); C, pereopod 3; D, pereopod 4; E, pereopod 5; F, pereopod 6; G, pereopod 7; H, uropod 1; I, uropod 2; J, telson; K, right and left uropod 3. Scales: 1 (A – g), 0.1 mm; 2 (H – J) 0.5 mm; 3 (K), 0.5 mm.

FIGURE 7. Wangiannachiltonia guzikae n. sp., paratype female, 2.6 mm. A, gnathopod 1; B, gnathopod 2; C, right and left uropod 3; D, oostegite on pereonite 2; E, oostegite on pereonite 3; F, oostegite on pereonite 4; G, oostegite on pereonite 5. Scales: 1 (A – B), 0.1 mm; 2 (C), 0.05 mm; 3 (D – G), 0.1 mm.

FIGURE 8. Wangiannachiltonia guzikae n. sp., morphological variety: A, distal end of male gnathopod 2 (Elizabeth Springs); B, uropod 2 (Old Finnis Springs); C, female pereopod 7 (Old Finnis Springs); D, distal end of male gnathopod 2 (Coward Springs); E, uropod 2 (Coward Springs).