Nitocrella karanovici, Tang, Danny & Eberhard, Stefan M., 2016

Tang, Danny & Eberhard, Stefan M., 2016, Two new species of Nitocrella (Crustacea, Copepoda, Harpacticoida) from groundwaters of northwestern Australia expand the geographic range of the genus in a global hotspot of subterranean biodiversity, Subterranean Biology 20, pp. 51-76 : 57-63

Taxon classification Animalia Harpacticoida Ameiridae

Nitocrella karanovici sp. n. Figs 5, 6, 7, 8, 9

Type locality.

Borehole UNK02 (23°15'00"S; 119°53'41"E), Ethel Gorge aquifer, approximately 15 km ENE of Newman (Fig. 1), Western Australia, 8 February 2011, P. Bell and S. Catomore leg.

Type material.

Holotype female (WAM C51837) in absolute alcohol, allotype male (WAM C51838) in absolute alcohol, 4 paratype females and 2 paratype males (WAM C51839-C51844) dissected and mounted on one slide each, and 26 paratype females, 28 paratype males and 1 copepodid (WAM C51845) in absolute alcohol.

Other material examined.

All material collected from boreholes in the Ethel Gorge aquifer, approximately 15 km ENE of Newman, Western Australia (Fig. 1). 3 females and 1 male (WAM C51833) in absolute alcohol, borehole EEX917 (23°19'47"S; 119°52'13"E), 8 February 2012, S. Catomore and N. Coen leg.; 7 females (WAM C51834) in absolute alcohol, borehole EEX917 (23°19'47"S; 119°52'13"E), 12 April 2012, P. Bell and S. Catomore leg.; 1 male (WAM C51835) in absolute alcohol, borehole P13S (23°18'56"S; 119°50'58"E), 21 November 2009, P. Bell and G. Perina leg.; 1 female (WAM C51836) in absolute alcohol, borehole T399 (23°17'03"S; 119°52'07"E), 5 November 2010, P. Bell and S. Catomore leg.; 13 females and 3 males (WAM C51846) in absolute alcohol, borehole UNK02 (23°15'00"S; 119°53'41"E), 9 February 2011, P. Bell and S. Catomore leg.; 2 females (WAM C51847) in absolute alcohol, borehole W105 (23°19'37"S; 119°51'50"E), 9 February 2011, P. Bell and S. Catomore leg.; 7 females (WAM C51848) in absolute alcohol, borehole W105 (23°19'37"S; 119°51'50"E), 13 April 2012, P. Bell and S. Catomore leg.; 3 females (WAM C51849) in absolute alcohol, borehole W105 (23°19'37"S; 119°51'50"E), 10 February 2012, S. Catomore and N. Coen leg.; 2 females (WAM C51850) in absolute alcohol, borehole W116 (23°14'47"S; 119°54'25"E), 8 February 2011, P. Bell and S. Catomore leg.; 3 females (WAM C51851) in absolute alcohol, borehole W116 (23°14'47"S; 119°54'25"E), 22 November 2009, P. Bell and G. Perina leg.; 5 females (WAM C51852) in absolute alcohol, borehole W116 (23°14'47"S; 119°54'25"E), 21 April 2010, P. Bell and G. Perina leg.; 8 females and 1 male (WAM C51853) in absolute alcohol, borehole W116 (23°14'47"S; 119°54'25"E), 8 February 2012, S. Catomore and N. Coen leg.; 6 females and 3 males (WAM C51854) in absolute alcohol, borehole W116 (23°14'47"S; 119°54'25"E), 11 April 2012, P. Bell and S. Catomore leg.; 1 female (WAM C51855) in absolute alcohol, borehole W79D (23°19'42"S; 119°50'39"E), 22 November 2009, P. Bell and G. Perina leg.; 3 females (WAM C51856) in absolute alcohol, borehole W79D (23°19'42"S; 119°50'39"E), 12 April 2012, P. Bell and S. Catomore leg.; 2 males (WAM C51857) in absolute alcohol, borehole WP126NRE (23°15'01"S; 119°53'42"E), 21 November 2009, P. Bell and G. Perina leg.

Description.

Female. Body (Fig. 5A) cylindrical, 450-495 µm (mean 471 µm; n = 6) long (measured from tip of rostrum to posterior margin of caudal rami) and 95-105 µm (mean 103 µm; n = 6) wide (at first free pedigerous somite). Prosome composed of cephalothorax and 3 free pedigerous somites. Urosome comprised of fifth pedigerous somite, genital double-somite, and 3 free abdominal somites. Components of genital double-somite (Fig. 5A, B, C) not fused dorsally but completely fused ventrally, with elliptical integumental window laterally, row of small spinules immediately posterior to each integumental window, and row of large spinules and frill of minute spinules encircling posterior margin; genital field with large median copulatory pore, chitinized copulatory duct leading anteriorly to pair of lobate seminal receptacles, and median genital pore covered by operculiform leg 6. First free abdominal somite with anteroventral pair of oval integumental windows and row of unequal spinules and frill of minute spinules ringing posterior border. Second free abdominal somite with row of subequal spinules and frill of minute spinules encircling posterior edge. Anal somite (Fig. 5B, D, E) with anterior and posterior row of spinules on ventral surface, several rows of spinules on lateral surface, and spinules along posterior margin of anal operculum.

Caudal ramus (Fig. 5B, D, E) about 1.5 times longer than wide, bearing 7 setae. Spinules present at insertion point of setae III, VI and VII. Setae IV and V spinulate, with proximal breaking planes; other setae naked. Seta VII basally tri-articulate.

Rostrum (Fig. 5F) about 1.25 times longer than wide, not demarcated at base, with rounded apex and 2 dorsal sensilla.

Antennule (Fig. 6A) similar to that of Nitocrella knotti sp. n.

Antenna (Fig. 6B), comprising coxa, basis, 1-segmented exopod, and 2-segmented endopod. Coxa naked and unarmed. Basis with 2 long spinules on inner margin and short row of minute spinules on anterior surface. Exopod armed with 3 pinnate setae (2 highly chitinized). Proximal endopodal segment naked and unarmed. Distal endopodal segment slightly longer than proximal endopodal segment; ornamented with row of spinules on proximal half of inner margin, 2 distolateral hyaline frills, and 2 distomedial spinules; armed distomedially with 2 naked unequal spines plus 1 long naked seta and apically with 1 pilose and 5 geniculate setae (lateralmost geniculate seta with 2 spinules at mid-point and fused basally with pilose seta).

Labrum (Fig. 6C) as in Nitocrella knotti sp. n., except shorter and with smaller denticles along distal margin.

Mandible (Fig. 6D) similar to that of Nitocrella knotti sp. n.

Maxillule (Fig. 6E) similar to that of Nitocrella knotti sp. n.

Maxilla (Fig. 6F) as in Nitocrella knotti sp. n., except with naked syncoxa.

Maxilliped (Fig. 6G) similar to that of Nitocrella knotti sp. n., except with only 1 row of spinules on syncoxa and no proximal seta on endopod.

Legs 1-4 biramous (Fig. 7A, B, C, D); leg 1 with trimerous rami; legs 2-4 with trimerous exopod and bimerous endopod. Armature on rami of legs 1 to 4 as follows (Roman numerals = spines; Arabic numerals = setae):

Leg 1 (Fig. 7A) intercoxal sclerite naked and concave on posterior margin. Coxa with 1 row of spinules on anterior surface and another row of spinules on posterolateral surface. Basis with row of long spinules at insertion of each ramus and 3 additional large spinules proximal to inner spine; both spines with subapical flagellum. Exopodal segments with large spinules along outer margin and on outer distal corner; middle segment also with fine spinules along inner margin. Endopodal segments with large spinules on outer margin and fine spinules along inner margin. Both setae on terminal exopodal segment and 1 of 3 setae on distal endopodal segment geniculate.

Leg 2 (Fig. 7B) intercoxal sclerite naked and posteriorly bilobate. Coxa with 1 row of minute spinules on posterolateral surface. Basis with row of spinules at insertion of each ramus and several fine spinules (only 1 depicted) on inner margin; outer spine with subapical flagellum. Exopod ornamented as in leg 1, except with additional spinulated frill on inner distal corner of proximal and middle segments. First two exopodal segments protruded on outer distal corner. Both endopodal segments with spinules along outer margin.

Leg 3 (Fig. 7C) similar to leg 2, except with outer seta (instead of spine) on basis and 3 elements on distal endopodal segment.

Leg 4 (Fig. 7D) similar to leg 3, except with much smaller spinules at insertion of endopod, 6 elements on distal exopodal segment (of which inner distal seta is longer and ornamented with tightly packed spinules on inner margin of apex), and 2 elements on distal endopodal segment.

Leg 5 (Fig. 7E) biramous. Basoendopod with long outer basal seta plus median pore, short row of spinules laterally and 4 distal spinulated setae on endopodal lobe. Exopod 1-segmented, about twice as long as wide, with spinules along inner margin and 4 setae (3 naked; 1 spinulated).

Leg 6 (Fig. 5B) represented by genital operculum covering genital pore, and armed with 1 minute naked seta on distolateral borders.

Male. Body length (measured from tip of rostrum to posterior margin of caudal rami) 400-440 µm (mean 417 µm; n = 7); body width 90-95 µm (mean 91 µm; n = 7). Prosome composed of cephalothorax and 3 free pedigerous somites. Urosome comprised of fifth pedigerous somite, genital somite and 4 free postgenital somites. Genital somite (Fig. 8A) wider than long, with elliptical integumental window laterally and row of small spinules immediately posterior to each integumental window. First postgenital somite (Fig. 8A) with ventral pair of oval integumental windows, posterior row of large spinules, and frill of minute spinules along posterior border. Second and third postgenital somites (Fig. 8A) posteriorly with row of spinules and frill of minute spinules. Anal somite (Fig. 8A) ornamented as in female. Caudal ramus (Fig. 8A) about 2 times as long as wide; armed and ornamented as in female.

Antennule (Fig. 8B) 10-segmented, haplocerate, with geniculation between segments 7 and 8. Armature as follows: 1, 10, 8, 2, 7 + ae, 2, 3, 4, 4, and 8. Short spinulate seta(e) with flagellate tip present on segments 5-7. Aesthetasc and adjacent apical seta on segment 5 basally fused forming acrothek. One (of 3) and 3 (of 4) elements on segments 7 and 8, respectively, modified as digitate spines. Two apical setae on segment 10 basally fused.

Inner spine on basis of leg 1 (Fig. 8C) modified as is typical for members of Ameiridae .

Leg 5 (Fig. 8D) biramous, with basoendopods fused medially. Basoendopod with outer basal seta and median pore and 2 apical spinulated elements on endopodal lobe. Exopod 1-segmented, about 1.3 times as long as wide, with 5 setae (3 naked; 2 spinulate).

Leg 6 (Fig. 8A) asymmetrical, with right side modified as operculum and left side basally fused to somite; each side armed with 2 unequal distolateral setae.

Variability.

One paratype female with discontinuous row of spinules along posteroventral margin of anal somite (Fig. 5B), but row is continuous in other paratype specimens. One dissected paratype female and 1 intact paratype male with 4 elements on terminal exopodal segment of leg 1 (Fig. 8E). One dissected and 1 intact paratype males with 3 elements on distal endopodal segment of leg 2 (Fig. 9C). One dissected paratype female with 4 elements on terminal exopodal segment of leg 3 (Fig. 8F). One dissected paratype female and 1 intact paratype male with 2 elements on distal endopodal segment of leg 3 (Fig. 8G). One dissected and 3 intact paratype females with longer inner distal spine on distal endopodal segment of leg 3 (Fig. 8H). One dissected and 3 intact paratype females plus 3 intact paratype males with 3 elements on distal endopodal segment of leg 4 (Fig. 8I). One intact paratype female with 1 element on distal endopodal segment of leg 4 (Fig. 8J). Two dissected and 1 intact paratype females with 3 (Fig. 9A) or 2 elements (Fig. 9B) on basoendopod of leg 5. Five intact paratype males with 1 (Fig. 9D) or no elements (not drawn) on basoendopod of leg 5. One intact paratype male with 3 setae on leg 6 (not drawn).

Etymology.

This species is named for Dr. Tomislav Karanovic, in recognition of his extensive taxonomic research on subterranean copepods of Australia.

Differential diagnosis.

Nitocrella karanovici sp. n. also belongs to the " vasconica "-group as it possesses the distinctive six armature elements on the distal exopodal segment of leg 4. Of the other 20 species in this group, Nitocrella karanovici sp. n. shares five armature elements on the distal exopodal segment of leg 1 with only Nitocrella dussarti Chappuis & Rouch, 1959 and Nitocrella gracilis Chappuis, 1955. Nitocrella karanovici sp. n. can be easily distinguished from Nitocrella dussarti by having three armature elements (instead of four) on the distal endopodal segment of leg 3 and four setae (instead of three) on both the exopod and basoendopodal lobe of leg 5 in the female, and from Nitocrella gracilis by having a short outer spine and long inner seta (rather than two subequal setae) on the distal endopodal segment of leg 2, two spines and one seta (instead of one spine and two setae) on the distal endopodal segment of leg 3, and four setae (instead of 3) on the basoendopodal lobe of leg 5 in the female.