Koekotroides, J.-P & Myers & Shepherd, 2025

J. - P, Olivier, Myers, Alan A. & Shepherd, Lara D., 2025, A new genus and six new species of endemic landhopper in the family Arcitalitridae (Amphipoda: Talitroidea) from New Zealand, Zootaxa 5691 (2), pp. 277-311 : 279-304

Koekotroides gen. nov.

Puhuruhuru ( Fenwick & Webber, 2008)

Genus A ( Ball et al. 2024)

Type species. Koekotroides moowhitihauuru sp. nov.

Included species. Koekotroides gen. nov. includes six species: Koekotroides moowhitihauuru sp. nov., K. taapinea sp. nov., K. tewhaarua sp. nov., K. pekehau sp. nov., K. ngaokiroa sp. nov. and K. maene sp. nov.

Description. Small to medium sized (body length 4–10 mm). Femipod. Males slightly smaller than females, recognisable by the presence of penes. Male g nathopod 1 basis narrowing proximally slightly more along the posterior margin than in females. Otherwise, sexual dimorphism negligible. Eye small (0.2–0.25 head length). Antenna 1 reaching to at least midpoint of peduncle article 5 of antenna 2. Maxilliped endopodite apex subacute or blunt; exopodite distally arcuate with subacute apex; palp article 2 without distomedial lobe; article 4 vestigial, or absent. Gnathopod 1 not sexually dimorphic; posterior margins of merus, carpus and propodus each without lobes covered in palmate setae. Gnathopod 2 propodus mitten-shaped in both sexes; posterior margin of merus, carpus and propodus each with lobe covered in palmate setae. Pereopods 3–7 simplidactylate. Oostegite setae with simple smooth tips. Pereopod 4 dactylus basidactylate. Pereopod 5 short, less than 0.6 times length of pereopod 6; dactylus not inflated. Pereopod 6 slightly shorter than pereopod 7. Gills on gnathopod 2 and pereopods 3–6. Pleonites 1–3 smooth without dorsal spines. Pleopods 1–3 biramous, decreasing in size posteriorally; peduncles naked, rami with no visible articulations. Epimeron 1 shallowest. Epimera 2–3 subequal in depth. Epimeron 3 ventral margin posteromedially weakly or strongly concave. Uropod 1 distolateral robust seta present; exopodite with no dorsal robust setae; endopodite with dorsal robust setae. Uropod 2 exopodite with no dorsal robust setae; endopodite with dorsal robust setae. Uropod 3 peduncle bulbous, with robust setae; ramus with robust setae, short relative to peduncle. Telson as broad as long, undulate, with dorsal and apical robust setae.

Etymology. Koeko = te reo Māori for tapering to a point, referring to the arcuate maxilliped exopodite, and troides a termination used in some other arcitalitrids.

Remarks. In Koekotroides gen. nov., gnathopod 1 lacks the lobes covered in palmate setae that are present on gnathopod 1 of males and females of most other Arcitalitridae . They are, however, also absent in the type genus Arcitalitrus Hurley, 1975 , in Insulariator Lowry & Myers 2019 , in Solitroides Suzuki, Nakano, Nguyen, Nguyen, Morino & Tomikawa 2017 and in Myanmarorchestia Hou & Zhao, 2017 . The single known species of Insulariator from Tasmania differs from Koekotroides gen. nov. in lacking spear-like robust setae on the propodus of gnathopod 1 and in the form of the pleopods that in Insulariator have broad peduncles and have rami with partial articulations. It also has a large eye, epimeron 3 without a concavity on the distal margin and an extraordinary elongate gnathopod 2 in both sexes. Koekotroides gen. nov. shares many character states with Arcitalitrus , but differs markedly in the form of the pleopods. In Arcitalitrus , the pleopod peduncles are broad and setose, the rami are articulated and heavily setose and pleopod 3 is very reduced, sometimes vestigial. Koekotroides gen. nov. is quite similar to the Vietnamese genus Solitroides . It shares with that genus the arcuate maxilliped exopodite, the spear-like robust setae on the gnathopod 1 propodus, the pleopods without setae on the peduncles and with rudimentary indication of articles on the rami and in the small, terminally setiferous oostegites. It differs from it in the broad, round termination of the exopodite of the maxilliped, the evenly convex ventral margin of epimeron 3 and the lack of long marginal robust setae on the telson. Myanmarorchestia is very different from Koekotroides gen. nov. in the form of the maxilliped which does not have an arcuate exopodite, its peculiar gills with their numerous filamentous projections, the nonbulbous uropod 3 peduncle and the telson lacking long marginal robust setae. Because of the unique gills, this genus could be placed in a new monophyletic family within the Protorchestoidae. For the moment, we retain it in the Arcitalitridae , which currently incorporates all the known world simplidactylate forest hoppers. Koekotroides gen. nov. has three autapomorphies that differentiate it from all other Arcitalitridae , the bulbous peduncle of uropod 3, the concave distal margin of epimeron 3 and the smooth margins of the pleopod rami with no indication of even rudimentary articulations.

Koekotroides gen. nov. consists of two species groups. Group 1 ( K. moowhitihauuru sp. nov., K. taapinea sp. nov., K. tewhaarua sp. nov. and K. maene sp. nov.) occurs on the Three Kings Islands, North Cape, Poor Knights Islands and in Auckland and Whanganui, while Group 2 ( K. pekehau sp. nov. and K. ngaokiroa sp. nov.) is limited to Te Paki, Ahipara and Maungataniwha Ecological Districts ( Fig. 1 ). Group 1 retains the more ancestral character state, having a distinct article 4 on the maxilliped palp. This character state is shared by all other world Arcitalitridae and Protorchestiidae except for the species in Group 2 of Koekotroides gen. nov. in which article 4 is lost. The loss of the maxilliped article 4 in Koekotroides gen. nov. is a homoplasy. It is not a synapomorphy with this character state in the Talitroidae.

Diagnostic key to the known species of Koekotroides Ball, Myers & Shepherd, 2025 (males and females)

1. Gnathopod 1 propodus posterior margin with 3 robust spear-like setae, telson with 3 dorsal robust setae, maxilliped endopodite apex subacute........................................................................................ 2

- Gnathopod 1 propodus posterior margin with 4 robust spear-like setae, telson with 2 dorsal robust setae, maxilliped endopodite apex rounded........................................................................................ 3

2. Propodus of gnathopod 1 with oblique palm (simple)......................................... K. ngaokiroa sp. nov.

- Propodus of gnathopod 1 with small but distinct palm (parachelate).............................. K. pekehau sp. nov.

3. Uropod 1 peduncle distolateral robust seta 0.4–0.5 x length of exopodite......................................... 4

- Uropod 1 peduncle distolateral robust seta ≤0.3 x length of exopodite............................................ 5

4. Epimeron 3 posterior margin distinctly crenulate, with fine setae............................... K. tewhaarua sp. nov.

- Epimeron 3 posterior margin almost smooth................................................... K. maene sp. nov.

5. Epimeron 2 posterior margin nearly straight along distal half, posterodistal margin with or without small process; epimeron 3 ventral margin moderately concave.................................................. K. moowhitihauuru sp. nov.

- Epimeron 2 posterior margin evenly concave along distal half, posterodistal margin drawn out into a long subacute process; epimeron 3 ventral margin barely concave.................................................. K. taapinea sp. nov.

Figures

FIGURE 1. Map of the North Island of New Zealand showing locations referred to in the present study.