Pseudolongiflagrum, Drumm & Heard, 2022

Drumm, David T. & Heard, Richard W., 2022, Mexctenapseudes boeschi, a new tanaidacean genus and species (Crustacea: Peracarida: Apseudomorpha: Parapseudidae) from the Mexican coast of Campeche with the designation of a new related Australian genus to receive Longiflagrum caeruleus (Boesch, 1973), Zootaxa 5116 (2), pp. 200-222 : 202-204

Pseudolongiflagrum n. gen.

Synonyms. Apseudes: Boesch (1973) (in part); Longiflagrum: Guţu (1995) (in part)

Diagnosis. Rostrum well-developed, acute. Hyposphenia strongly developed. Antenna with peduncle article-1 without antero-medial tooth-like projection. Labial palp with three distal spiniform setae. Mandibular palp article-1 with mixture of plumose and simple setae. Cheliped basis with mid-ventral margin having spiniform seta. Pereopod-1 having propodus with two and five, well-developed spiniform setae on dorsodistal and ventral margins, respectively; dactylus well-developed, length greater than propodal width. Pleonite-1 anteriorly having mediallyinterrupted, transverse small setulate setae; pleonites 2–5 lacking transverse row of setae. Pleopodal rami only marginally foliaceous, not broadly expanded distally.

Etymology. Pseudo = false + generic name Longiflagrum. The gender is neuter.

Diagnostic description (extracted from description and illustrations of Boesch 1973).

Rostrum ( Fig. 1A, D ) well-developed, about one third length of post-ocular carapace; lateral margins slightly convex, attenuated anteriorly forming narrow acute tip.

Pereonal hyposphenia on male strongly developed mid-ventrally on pereonites 1–6 ( Fig. 1C ); on incubatory female reduced or absent on pereonites 3–5; on pereonites 1 and 6 similar to male ( Fig. 1F ).

Pleon having pleonite-1 with incomplete transverse, anterodorsal row of short setulate setae, interrupted middorsally ( Fig. 1B, E ); pleonites 2–5 lacking anterodorsal row of setae.

Pleotelson with lateral margins with few small setae, posterior margin forming rounded lobe not extending past uropodal peduncles; male with length about equal to width and length about equal to combined lengths of last three pleonites; female having width slightly more than length and length about equal to combined lengths of pleonites 2 to 5.

Antennule ( Fig. 1G ) with rami subequal, outer ramus slightly shorter.

Antenna ( Fig. 1H ) with peduncle article-1 without antero-medial tooth-like projection.

Mandible ( Fig. 1I ): palp article 1 with inner margin bearing cluster of plumose setae, articles 2 and 3 with long simple setae and short pectinate setae; article-2 shorter than article 3.

Labial palp with three distal spiniform setae.

Maxilliped ( Fig. 1J ) with basis having distolateral subacute process; palp article-1 short, much wider than long, about ¼ length of article-2, outer margin forming narrow lobe with two distal setae.

Cheliped sexually dimorphic, male cheliped ( Fig. 1K ) much larger and more massive than that of female ( Fig. 1L ), generally similar to males and females of Ctenapseudes and Longiflagrum; basis in both sexes having stout spiniform seta on mid-ventral margin; exopod with penultimate article asetose.

Pereopod-1 sexually dimorphic; male ( Fig. 1M ) narrower and less robust than in female ( Fig. 1N ); basis with ventral distal margin having distinct spiniform seta and two to four simple setae; merus having dorsodistal margin with small lobe bearing long, strongly developed spiniform seta and having ventral distal margin with short, stout spiniform seta; carpus with dorsodistal margin expanded dorsodistally forming shallow lobe extending slightly over base of propodus and armed distally with long strongly-developed spiniform seta, ventral margin bearing two short stout spiniform setae; propodus longer than broad, having dorsodistal margin with two spiniform setae adjacent to dactylus, ventral margin with four or five elongate spiniform setae (anterior most adjacent to dactylus); dactylus well-developed, longer than propodal width and shorter than length; ventral margin with three minuscule, buttressed, spiniform setae, tip terminating in small nail: female pereopod-1 ( Fig. 1N ): with articles having same pattern of spiniform setae as in male; except for dactylus, broader; merus and carpus with dorsodistal margin each bearing relatively stout and short spiniform seta and not forming distinct lobe; propodus short, broader than long, with distal margin rounded; dactylus development and morphology as in male, but relatively longer than propodal length and shorter than its width.

Pereopod-4 ( Fig. 1O ) with dactylus distinct, but smaller than those of pereopods 2,3, and 5. Pereopod-6 ( Fig. 1P ): (in posterior orientation) with basis having sparce row of five or six plumose setae along ventral mid-margin; entire dorsal margin having row of numerous setulate or plumose setae.

Pleopods ( Fig. 1Q ): five well-developed pairs, basal article, and rami with numerous plumose setae; marginally foliaceous, rami elongate, sub-rectilinear, not distally expanded or broadly rounded, as in Longiflagrum estuarius ( Boesch, 1973).

Type species. Pseudolongiflagrum caeruleus ( Boesch, 1973) n. comb.

Synonyms. Apseudes caeruleus Boesch, 1973 ; Longiflagrum caeruleus: Guţu (1995) .

Remarks. Pseudolongiflagrum n. gen. is distinguished from the somewhat similar and apparently related Ctenapseudes Bamber, Ariyananda & Silva, 1997, Longiflagrum Gutu 1995, and the new monotypic Mexican genus designated here, by a combination of characters ( Table 2 ), which includes (1) well-developed pereonal hyposphenia (absent or poorly developed in the other three genera), (2) the mandibular palp with plumose setae on article-1 (simple setae in the other three genera), (3) the mandibular palp article-3 longer than article-2 (article-3 shorter than article- 2 in the other three genera), (4) the cheliped basis having a distinct spiniform setae on the mid-ventral margin (not present in the other three genera); and (5) the pereopod-1 with a distinctive, well-developed dactylus (reduced in Ctenapseudes and Longiflagrum). For further differences and comparisons refer to Remarks under diagnosis of the new Mexican genus below, and the key to distinguish the genera of the subfamily Parapseudinae .

Figures

FIGURE 1. Pseudolongiflagrum caeruleus (Boesch, 1973) n. comb. (modified from Boesch 1973). Adult male holotype (8.6 mm): A, habitus, dorsal view; B, enlargement of pleon; C, lateral view of pereon showing hyposphenia; G, antennule; H, antenna; I, mandibular palp; J, maxilliped; K, cheliped; M, pereopod-1; O, pereopod-4; P, pereopod-6; Q, pleopod-1.Adult female (10.8 mm): D, habitus, dorsal view; E, enlargement of pleon; F, lateral view of pereon showing reduced hyposphenia; L, cheliped; N, pereopod-1.