Diacyclops tomlinsonae Karanovic 2024, sp. nov.

Diacyclops tomlinsonae sp. nov. (Figs. 1E, 22–25) urn:lsid:zoobank.org:act: FB1207A7-C319-489E-AA46-D6F85B4D0AEB Type locality. Australia, New South Wales, Tamworth, bore 93024, sample no. 7T27P100-200, 31.26435°S 151.20272°E, 17 July 2007, collected by M. Tomlinson. Holotype. Adult female dissected on 1 microscope slide. Paratypes. One male, 1 female, and 1 copepodid from type locality dissected on 1 microscope slide each; 3 males and 3 females from type locality on 1 SEM stub (row no. 3), together with 5 other species described here; 16 males, 5 females, and 4 copepodids from type locality in 1 alcohol vial; 10 males, 3 females, and 1 copepodid from type locality in 1 alcohol vial; 1 female from type locality, but collected on 30 January 2007 by M. Tomlinson, dissected on 1 microscope slide; 1 male and 3 females from type locality, but collected on 30 January 2007 by M. Tomlinson, in 1 alcohol vial. Etymology. The species is named after Dr. Moya Tomlinson, Australian Rivers Institute, Griffith University, Nathan, who collected this species and entrusted it to me for identification. The name is a noun in the genitive singular. Diagnosis. Female. Body length from 355 to 420 µm. Habitus (Figs. 1E, 24A) slender, more than 3.1 times as long as wide, with prosome/urosome ratio of about 1.35, and cephalothorax 1.83 times as wide as genital double-somite in dorsal view. Integument on all somites (Fig. 24A, B, C) thin and smooth, with almost no bacterial cover; general distribution of spinules and cuticular pores on somites as in D. leijsi. Hyaline fringes of prosomites (Fig. 24A) and urosomites (Figs. 22A, 24B, C) smooth. Genital double-somite (Figs. 22A, 24B) about as long as wide, widest at first quarter of its length and gradually tapering posteriorly, widest part about 1.5 times as wide as posterior margin; seminal receptacle small and butterfly-shaped, posterior part greatly reduced; copulatory pore small and located at about 2 fifths of somite length; copulatory duct narrow, long, and weakly sclerotized. Anal somite (Figs. 22A, 24C) with large spinules along ventral and lateral margins. Caudal rami (Figs. 22A, 24D) of medium length and stout, narrowly spaced, about 2.75 times as long as wide and about twice as long as anal somite; principal terminal setae with breaking planes, inner one about 0.9 times as long as entire urosome and 1.45 times as long as outer one; dorsal seta about 1.2 times as long as caudal ramus, 2.6 times as long as innermost terminal seta, and 3 times as long as outermost terminal seta. Antennula (Fig. 22B) 11-segmented, half as long as cephalothorax, with single aesthetasc on penultimate segment and setae formula 8.4.8.3.2.2.2.2.2.2.8; ultimate segment about 1.4 times as long as wide. Antenna (Figs. 22C, 24E) 5-segmented, without exopodal seta, with setae formula 0.1.1.5.7; second segment about 1.6 times as long as fifth segment. Labrum (Fig. 24E) with 2 diagonal rows of 8 slender spinules each on anterior surface; cutting edge slightly concave, with 16 sharp teeth between blunt and smooth lateral corners. Mandibula (Fig. 22D) similar to that in D. leijsi, but with much shorter dorsalmost seta on cutting edge. Maxillula (Figs. 22E, 24E) also similar to that in D. leijsi, but with shorter and slightly inflated coxobasis. Maxilla (Figs. 22F, 24E) similar to that in D. leijsi, but with shorter basis; basal claw shorter than strong basal seta. Maxilliped (Figs. 22G, 24E) small, slender, with setae formula 2.1.1.2. Shape and segmentation of swimming legs (Figs. 22H, 23A, B, C, D, E; 24F) as in D. leijsi, except exopod of first leg 2-segmented and all legs much shorter; basis of first leg with long outer seta and short inner spine, latter slightly shorter that first endopodal segment; basis of second to fourth legs with slightly shorter outer seta and inner distal corner blunt; all first exopodal segments without inner seta; second exopodal segment of second to fourth legs, all first endopodal segments, and second endopodal segment of first and second legs with single inner seta; second endopodal segment of third and fourth legs with 2 inner setae; ultimate exopodal segments spine formula 3.3.3.3 and setae formula 5.4.4.4; third endopodal segments of first to third leg with 2 inner setae, 1 subapical seta, 1 apical spine, and 1 outer seta; third endopodal segment of fourth leg 1.2 times as long as wide, with 2 inner setae, 2 apical spines, and 1 outer seta; its outer spine about 1.3 times as long as segment and slightly more than twice as long as inner spine. Fifth leg (Fig. 22A) shape and segmentation as in D. leijsi, but second segment only 1.4 times as long as wide and about 0.7 times as long as its spine. Sixth leg minute, but with two well-articulated spines; outermost seta half as long as plate width and about 4 times as long as spines. Male. Body length from 330 to 370 µm. Habitus (Fig. 25A) and urosome (Fig. 23F) slightly slenderer than in female; free genital somite (Fig. 23F) less than 1.3 times as wide as subsequent urosomite, with large ovoid spermatophores filling almost entire somite. Ornamentation of cephalothorax, free prosomites, and last 3 urosomites (Fig. 23F, 25C, D, F) as in female. Caudal rami (Figs. 23F, 25D) slightly slenderer than in female, but proportion of setae without any significant difference. Antennula (Figs. 23G, 25B, E) segmentation and armature same as in D. hancocki, but all segments much shorter; penultimate segment only slightly longer than wide. Antenna, labrum, mandibula, maxillula, maxilla, maxilliped, all swimming legs (Fig. 23H), and fifth leg (Fig. 23F) as in female. Sixth leg (Figs. 23F, 25C, F) almost perfectly semicircular, outermost seta about 2.2 times as long as central seta, which in turn about 3.3 times as long as minute innermost spine. Variability. One paratype female from bore 93024, collected on 30 January 2007, had a slightly shorter outer apical spine on the third endopodal segment of the fourth swimming leg (Fig. 23E).