Maliithipon wellsi, Cottarelli & Bruno, 2021

Cottarelli, Vezio & Bruno, Maria Cristina, 2021, Interesting interstitial Paramesochridae (Copepoda: Harpacticoida): Maliithipon wellsi gen. et sp. nov. from the Philippines, M. aberrans (Mielke, 1984) comb. nov from Panama, and M. cf. aberrans (Mielke, 1984) from the Azores, Zootaxa 5051 (1), pp. 68-93 : 73-80

publication ID	https://doi.org/ 10.11646/zootaxa.5051.1.7
DOI	https://doi.org/10.5281/zenodo.5573066
persistent identifier	https://treatment.plazi.org/id/270F87BB-FF8A-FFCA-0ECC-0434FE56F3C4
treatment provided by	Plazi
scientific name	Maliithipon wellsi
status	sp. nov.

Treatment

Maliithipon wellsi sp. nov.

( Figs. 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

zoobank.org:act: 89A4C254-A4EA-4E91-A89B-FE2F5045216B

Type locality. Philippines, Batangas Province, Verde Island. Station 1 (13°31’36.03”N, 121°04’45.68”E), beach in Saint Agapito Village. Station GoogleMaps 2 (13°34’02.65”N; 121°03’56.64”E) on the opposite side of the island, on Mahabang Buhangin beach, in the Barangay area , near San Augustin village GoogleMaps .

Type material. Holotype: female, undissected, mounted on one slide labelled: Maliithipon wellsi , holotype female (reg. no. NHMUK 2019.1002), Isla Verde, station 1, 4/VIII/1995. Paratypes: one male, undissected, mounted on one slide labelled: Maliithipon wellsi , paratype male (reg. no. NHMUK 2019.1003), Isla Verde, station 1, 4/VIII/1995. One female dissected, mounted on slide labelled: Maliithipon wellsi , paratype female (reg. no. NHMUK 2019.1004), Isla Verde, station 1, 4/08/1995. Two females, undissected, each one mounted on one slide labelled: Maliithipon wellsi , paratype female (reg. nos NHMUK 2019.1005–1006), Isla Verde station 1, 4/VIII/1995. Two females, undissected, each one mounted on one slide labelled: Maliithipon wellsi , paratype female (reg. nos NHMUK 2019.1007–1008), Isla Verde station 2, 4/VIII/1995. Two females, undissected, each one mounted on one slide labelled: Maliithipon wellsi , paratype female ( DIBAF), Isla Verde station 1, 4/VIII/1995.All material collected by V.C.

Etymology. The new species is named in honour of Prof. John B. J. Wells, in appreciation of his outstanding contribution to the study of copepods. The specific epithet is a noun in the genitive singular. Gender masculine.

Description of female (holotype). Habitus ( Fig. 1A View FIGURE 1 ): body elongate, cylindrical and slightly depressed dorsoventrally, naupliar eye absent. Length: 300–350 μm; n = 5, mean = 331 μm. Length of the holotype: 349 μm. Last urosomites tapering posteriorly; prosome to urosome ratio: 0.90; free pedigerous somites without any lateral or dorsal expansions, all connected by well-developed arthrodial membranes. Integument weakly sclerotized, cuticle finely pitted dorsally ( Fig. 2D View FIGURE 2 ). First pedigerous somite and dorsal cephalic shield fused forming cephalothorax representing about 25% of the total body length. Cephalothorax and somites with few sensilla and several pores on dorsal, lateral and ventral surfaces (pores were difficult to observe, their pattern could not be precisely determined) ( Figs. 1A View FIGURE 1 , 2D View FIGURE 2 ). Second and third urosomite completely fused to form genital double-somite ( Figs. 2A–C View FIGURE 2 ).Penultimate body somite without sensilla, carrying a fine, well developed lobate pseudoperculum ( Figs. 1A View FIGURE 1 , 2D View FIGURE 2 , 3A–B View FIGURE 3 ). Anal somite small, with pair of dorsal sensilla ( Fig. 3A–B View FIGURE 3 ); anal operculum not visible. Genital field ( Fig. 2A–C View FIGURE 2 ) small, ellipsoidal, located mid-ventrally and slightly above the mid-length of the genital double-somite, surrounded by eight pores of different size; P6 ( Fig. 2B–C View FIGURE 2 ) reduced to two small arched plates not fused to each other; copulatory pore opening below them.

Caudal rami ( Figs. 1A View FIGURE 1 , 2D View FIGURE 2 ). Elongated, slightly tapering posteriorly and slightly divergent, three times the length of the last urosomite; length: 31 μm; length/width: 2.7. Armature represented by six setae (seta I apparently missing): seta II short and very thin; seta III stout and pointed, unipinnate in approximately one/fifth of the distal outer margin; seta IV very small, bare, enlarged in the first half and thin in the second half; seta V unipinnate, enlarged in the first half and thin in the second half; seta VI as seta III but shorter; seta VII bare, bi-articulate at base and arising distally at two/third of the ramus.

Rostrum ( Fig. 1A View FIGURE 1 ). Small, approximately triangular, with round tip, fused to cephalic shield, armed with two sensilla.

Antennule ( Figs. 1A View FIGURE 1 , 3E View FIGURE 3 ). Short, robust, 8-segmented. First segment longest, without armature, with a row of inner spinules. Second segment with three pinnate and one bare seta on the inner margin, one long seta on the outer margin. Third segment provided with three pinnate and two bare setae. Inner distal corner of fourth segment forming a sub-cylindrical process provided with a group of one long slender bare seta, one short spindle-like pinnate seta, one long and thick aesthetasc, fused at base with a long slender seta. Fifth segment smallest, with one pinnate and one bare seta arising from a sub-cylindrical inner outgrowth. Sixth segment with five bare setae; seventh segment with five bare setae, the longest and strongest one originating from a ventral cylindrical outgrowth. Last segment wider than long, furnished with seven bare setae and a lateral acrothek formed by a slender aesthetasc and a seta fused at base. Armature formula: 1–[0], 2–[2 bare + 3 pinnate], 3–[2 bare + 3 pinnate], 4–[2 bare + 1 pinnate + ae], 5–[1 bare + 1 pinnate], 6–[5 bare], 7–[5 bare], 8–[7 bare + acrothek].

Antenna ( Fig. 3C–D View FIGURE 3 ). 4-segmented; coxa small and bare; basis approximately three times longer than wide, without any surface ornamentation; exopod ( Fig. 3D View FIGURE 3 ) 1-segmented, with a constriction at half-length (trace of segmentation?), two bare setae laterally, one bare and one pinnate seta apically. Endopod 2-segmented, proximal segment with one pinnate abexopodal seta; distal endopodal segment ornamented with two groups of spinules on lateral margin and armed with one bare spiniform seta sub-distally, four long and geniculate setae, two shorter bare ones.

Mandible ( Fig. 4A View FIGURE 4 ). Coxa with well-developed gnathobase bearing one pinnate seta at dorsal corner; cutting edge provided with one long pointed tooth on outer corner, four apical long needle-like teeth, and one pointed, strong tooth on inner corner, half as long as coxal length. Palp reduced, 2-segmented, comprising basis with distal pinnate seta, 1-segmented endopod with two distal setae of subequal length, two short lateral pinnate setae.

Maxillule ( Fig. 4B View FIGURE 4 ). Praecoxal arthrite well developed, quadrangular, with one pinnate proximal seta on lateral margin, three thin bare setae, three pointed teeth at distal margin. Coxa prolonged in a cylindrical endite with apical pinnate seta; basis with one subapical unipinnate seta and one apical unipinnate spiniform seta. Exopod and endopod missing.

Maxilla ( Fig. 4C View FIGURE 4 ). Overall very large compared to the other mouthparts; syncoxa with three endites, proximal one reduced to a large pinnate seta, median endite with one apical pinnate seta, distal coxal endite with one bare and one pinnate apical seta. Allobasis prolonged into strong denticled claw; endopod fused to basis and armed with one claw-like unipinnate seta and four naked setae distally.

Maxilliped ( Fig. 4F View FIGURE 4 ). 3-segmented, comprising syncoxa, basis, and 1-segmented endopod; syncoxa bare, basis more than twice the length of coxa and bare, length/width: 2.9; endopod small, with one small subapical spine, one strong claw-like pinnate seta and two thinner bare ones distally.

P1 ( Fig. 4G View FIGURE 4 ). Intercoxal sclerite long and thin, slightly concave; coxa bare, well-developed and pyramidal; basis without outer seta, with bare inner seta at half length of the inner margin; exopod and endopod 2-segmented, exopod slightly shorter than endopod. First exopodal segment longer than the second one, with spinular row along outer margin, strong pinnate seta on distal outer corner; second segment with spinular row along outer margin, four distal pinnate setae, the innermost is the longest. First endopodal segment bare, 2.5 times longer than the second one, with spinules along inner and outer margin; second segment with spinules along the distal part of the outer margin, two long geniculate apical setae.

P2–P4. ( Fig. 5A–C View FIGURE 5 ). Intercoxal sclerites long and thin. P2 basis without outer seta and with a proximal inner row of hair-like spinules; P3 and P4 basis with outer pinnate seta. Exopods 3-segmented, first, second and third segments with spinular row along outer margin; first segment with outer unipinnate, curved spine at distal corner; third segment also with long geniculate apical seta. Endopods missing. Setal formula provided in Table 1. View TABLE 1

P5 ( Fig. 2A–B View FIGURE 2 ). Reduced to a lobed plate, with one short seta (ancestral baseoendopodal seta) and a tiny tip.

Description of male (paratype). Habitus ( Fig. 1B View FIGURE 1 ) General body shape and ornamentation as in female, but slightly smaller and more slender than in female, body length 252 μm; largest width measured at posterior margin of cephalic shield: 44 μm; prosome to urosome ratio: 0.83. Cephalothorax representing about 26% of total body length. Antenna, Mdb, Mxl, Mxpd, P1–P4 as in female, sexual dimorphism in separation of genital somite, A1, Mx, P5, and P6, P2 basis ornamentation and P3–P4 basis armature.

Caudal rami ( Fig. 3F View FIGURE 3 ). Shape and armature as in female but proportionally longer (lenght/width = 3.2).

Antennule ( Fig. 5E View FIGURE 5 ). Strong, short, subchirocer, 7-segmented. Armature cannot be described since some of the setae are damaged or missing in the only existing specimen. First segment apparently without distal seta. Fifth segment enlarged, square, with longer and thinner aesthetasc than in female; seventh segment with thin distal aesthetasc, two of the observable four setae are small.

Maxilla ( Fig. 4D View FIGURE 4 ). Structure and ornamentation as in female, but endopodal setae all bare.

P2. Basis without proximal row of hair-like spinules.

P3–P4. Basis with outer bare seta.

P5 ( Fig. 5D View FIGURE 5 ). Extremely reduced, represented by a small round lobe without armature.

P6 ( Fig. 5D View FIGURE 5 ). Two asymmetrical (the right one is larger) roundish plates without armature.

Spermatophore ( Fig. 5F View FIGURE 5 ). Ellipsoidal, slightly longer than the somite carrying the P5.

Variability. In one female paratype the caudal seta V is reduced in size (it equals seta IV) and there is a pore near seta VII ( Fig. 3B View FIGURE 3 ). In a second female paratype, the maxillary endopod carries one seta less ( Fig. 4E View FIGURE 4 ). In a third female paratype the P5 is unilobed and unarmed and the number and position of pores on the ventral surface of the genital somite differ ( Fig. 2C View FIGURE 2 ) .