Mexicope maletensis Riehl & Schienbein, 2024

Riehl, Torben, Schienbein, Katharina Ellen & Mifsud, Constantine, 2024, A new species of Mexicope Hooker, 1985 (Crustacea, Isopoda) — the first record of Acanthaspidiidae Menzies, 1962 from the Mediterranean Sea, Biodiversity Data Journal 12, pp. e 121508-e 121508 : e121508-

Mexicope maletensis Riehl & Schienbein sp. nov.

Materials

Type status: Holotype. Occurrence: catalogNumber: SMF 62000 ; individualCount: 1; sex: male; lifeStage: adult; preparations: whole animal (ETOH); occurrenceID: 58A3B6CC-79D2-5622-B2FA-A132124BDCE7; Taxon: scientificName: Mexicope maletensis Riehl and Schienbein ; phylum: Arthropoda; class: Malacostraca; order: Isopoda ; family: Acanthaspidiidae ; genus: Mexicope ; specificEpithet: maletensis ; scientificNameAuthorship: Riehl & Schienbein; nomenclaturalCode: ICZN; Location: higherGeography: Mediterranean; islandGroup: Maltese shelf; locality: off Ġnejna Bay ; verbatimDepth: 120 m; verbatimLatitude: 35 ° 56.014 ' N; verbatimLongitude: 14 ° 19.325 ' E; decimalLatitude: 35.93356667; decimalLongitude: 14.32208333; Identification: identifiedBy: Torben Riehl, Katharina E. Schienbein; Event: samplingProtocol: custom-built rectangular dredge, 1 m wide, 20 cm high and with 500 µm mesh size; eventDate: 07-06 - 2017; Record Level: institutionCode: SMF; basisOfRecord: PreservedSpecimen

Description

Body (Fig. 2 , Suppl. material 2) elongate; cuticular ornamentation small, rounded; lateral projections spine-like; length 2.5 mm; width 0.4 length; lateral margins subparallel, notched in Prn 3 and 4, spiny, pereonite 1 widest; tergites covered with scattered simple setae; relative widths of body segments: Ceph <Prn 1> Prn 2> Prn 3> Prn 4 <Prn 5> Prn 6> Prn 7> Plt (Table 2 ). Ceph (Figs. 3–4) length 0.44 width, 0.16 body length; frontal margin rounded; frons anterior margin rounded-triangular, projecting. Eyestalks present, width 0.60 length, ocelli present. Rostrum length 0.10 Ceph length.

Prn (Fig. 2 ) tergites medially with 2–4 conspicuous long setae; sternites each with 1 spine. Prn 1 length 0.21 width, 0.09 body length; lateral projection single, prominent, projection length 2.0 Prn 2 projection length; anterolateral margin smooth; posterolateral margin serrated. Prn 2 length 0.23 width, 0.09 body length; lateral projection single, anterolateral margin smooth, posterolateral margin serrated. Prn 3 and 4 subsimilar, length 0.20 and 0.21 width, respectively, 0.08 body length; lateral projections bifid, anterolateral and posterolateral margins serrated. Prn 5 length 0.15 width, 0.06 body length. Prn 6 length 0.23 width, 0.09 body length. Prn 7 length 0.20 width, 0.07 body length; Prn 5-7 lateral projections single, anterolateral margins serrated, posterolateral margins smooth.

Plt (Fig. 2 ) length 1.1 width, 0.33 body length; proximal quarter narrow, lateral margins in proximal quarter convex, increasingly wide towards posterior, lateral margins posterior quarter narrowing, lateral margins convex; posterolateral margin concave at Urp insertion; posterior apex protruding, convex, width 0.23 Plt width, length 0.44 Urp protopod length; lateral margins with 4 spine-like setae; surface and margins with simple setae.

AI (Fig. 3 B) length 0.20 body length, peduncular articles 1–2 elongated, article 3 cylindrical. Article 1 length 2.4 width, distally with 1 simple seta; article 2 length 4 width, 1.2 article 1 length, distally with 1 broom seta, 2 setae, broken, missing; article 3 length 1.0 width, 0.2 article 2 length; flagellum with 5 progressively narrower articles, length of articles 1 <2> 3> 4> 5 (Table 3 ); terminal article distally with 1 simple, long seta, 3 aesthetascs, 3 setae, broken, missing.

AII (Fig. 3 A) length 0.80 body length. Article 4 distally with 5 simple setae. Article 5 longer than proximal 4 articles together, dorsal margin with 4 simple, long setae, ventral margin distally with 1 simple seta, 1 seta broken, missing. Article 6 length 1.1 article 5 length, with 19 long, simple setae, 3 broom setae. Flagellum with 12–13 articles; first article as long as carpus (peduncular article 6), length 1.4 joint length of flagellum articles 2–12, rich in aesthetascs. Aesthetascs narrow, tubular.

Md (Fig. 4 C and D) slender, length 0.20 width, incisor of left and right Md with 5 cusps. Lacinia mobilis with 4 cusps. Spine row of left and right Md with 6 denticulate spine-like setae, progressively increasing in length and number of denticles from distal to proximal end of spine row. Pars molaris slender, with 4 simple setae on left and 3 simple setae on right Md; palp absent. MxI (Fig. 4 F) exopod length 5.7 width; margin with row of 12 simple setae, apex obliquely truncate, with 15 spine-like setae; endopod length 0.83 exopod length, length 8.3 width, medial margin with a row of 8 long, simple setae, apex narrow, with 1 serrated, spine-like and 2 simple, spine-like seta. MxII (Fig. 4 E) both parts of exopod laterally flexed, exopod length 1.1 endopod length, lateral part slightly longer than mesial part; lateral part apex with 1 long, serrated and 3 simple, spine-like setae; mesial part apex with 3 long, serrated spine-like and 1 simple, spine-like setae; endopod slightly wider than mesial and lateral part of exopod, densely covered with long, simple setae, apically with 3 serrated, spine-like setae.

Mxp (Fig. 4 A, B and Fig. 5 ) length 0.21 body length; basis and endite wide, basis length (excluding endite) 1.5 width, asetose, 2 receptaculi; endite ventrally densely covered with simple setae, distal margin ventrally with 2 unequally bifid spine-like setae and 1 equally bifid spine-like seta; epipodite short, reaching half way to palp articulation, acute apex, asetose, length 0.56 maxilliped length, 2.6 width; palp with 5 articles, length 0.52 maxilliped length, articles progressively narrower, merus with 2, carpus with 2, propodus with 4, dactylus with 5 sensillae.

P (Figs 6 , 7 , 8 ) uniformly baculiform, ambulatory legs, length PI <II> III <IV <V <VI> VII, PII length 0.60 body length, PVI length 0.70 body length; carpi and propodi similarly long, ventral margins distodorsally with row of 1–4 robust UB setae; propodi distodorsally with 1 unequally bifid, spine-like seta; dactyli with 1 fringed sensilla between claws, distodorsal claw about half as long as dactylus, slender and acute, curved ventrally, distoventral claw length 0.80 distodorsal claw length or shorter.

PI (Fig. 6 A) basis proximally with 1 submarginal whip seta; ischium dorsal margin with 2 whip setae, ventral margin with 1 whip seta; merus dorsal margin with 1 simple seta, ventral margin with 2 whip setae, mediodorsally with 1 simple seta; carpus dorsal margin medially with 1 whip seta, distally with 2 whip setae; ventral margin with 6 setae: 3 simple, 2 robust UB setae, 1 seta broken, missing; ventrally-submarginally with 2 simple setae; propodus dorsal margin medially with 1 robust UB seta, distally with batch of 1 broom seta and 2 whip setae; ventral margin with 3 robust UB setae and 1 whip seta; ventrally submarginally medially and laterally with, respectively, 1 simple seta, distolaterally with 1 simple seta; dactylus with 2 whip setae distodorsally.

PII (Fig. 6 B) basis dorsal margin proximally with 1 broom seta; distoventrally with 1 whip seta; ischium dorsal margin with 1 seta, broken; ventral margin with 2 whip setae; distal margin anteriorly and posteriorly respectively with 1 simple seta; merus dorsal margin proximally with 1 whip seta, distally with 2 whip setae; ventral margin with 2 whip setae; distally submarginally with 1 simple seta; carpus dorsal margin with 4 setae: 3 whip setae, 1 broom seta; distally submarginally with 2 simple setae, laterally and medially, respectively; ventral margin with 3 setae: 1 whip, 2 UB; propodus dorsal margin with 5 whip setae; ventral margin medially with 3 UB setae, distally with 2 whip setae; distally submarginally with 1 whip seta; dactylus dorsally subdistally with 3 whip setae, ventrally submarginally with 1 whip seta.

PIII (Fig. 6 C) basis dorsal margin with 1 whip seta and 1 broom seta; ventral margin with 3 simple setae; ischium dorsal margin with 1 simple seta, distal margin anteriorly and posteriorly, respectively, with 1 whip seta; ventral margin with 2 whip setae; merus dorsal margin distally with 1 simple seta; ventral margin distally with 1 simple seta; distal margin posteriorly with 1 whip seta; carpus dorsal margin distally with 1 broom seta; ventral margin medially with 1 whip seta, 1 robust UB seta, distal margin anteriorly and posteriorly, respectively, with 1 whip seta; medially submarginally with 2 simple setae, anteriorly and posteriorly, respectively; propodus dorsal margin medially with 1 seta, broken, missing, distally with 1 simple seta; ventral margin medially with 1 robust UB seta, distally with 1 robust UB, 1 whip seta; dactylus dorsal margin with 4 whip setae; distally anteriorly with 2 setae, broken, missing.

PIV (Fig. 7 A) basis proximodorsally with 1 simple seta, distoventrally with 1 simple seta; ischium dorsally with 2 simple setae submarginally; merus distodorsally with 2 simple setae; ventral margin proximally with 1 simple seta, distally with simple setae; carpus dorsal margin medially with 1 simple seta, distally with 2 simple setae, 1 broom seta, 1 seta, broken, missing; ventral margin medially with 1 simple seta, 2 robust UB setae; distal margin with 3 simple setae; propodus dorsal margin with 1 whip, 1 robust UB, 1 broom seta; ventral margin with 3 robust UB setae; dactylus dorsal margin with row of 3 simple setae and 1 UB seta, distally with 1 whip seta.

PV (Fig. 7 B) basis dorsal margin with 1 broom seta, 2 setae, broken, missing; ventral margin with 3 whip setae, distal margin with 1 simple seta; ischium dorsal and ventral margins with 2 whip setae, respectively; distal margin with 2 whip setae; merus dorsal margin distally with 1 whip seta, submarginally medially with 1 seta, broken, missing and 1 simple seta, distally with 1 simple seta; ventral margin proximally with 1 simple seta, distally with 1 whip seta and 1 simple seta; carpus dorsal margin medially with 2 whip setae, distally with 2 whip setae and 1 broom seta; ventral margin with 1 robust seta and 3 robust UB setae; distal margin posteriorly with 1 simple seta; propodus dorsal margin with 1 robust UB seta, 5 simple setae and 1 broken seta; ventral margin proximally with 1 seta, broken, missing, 3 UB setae, submarginally with 3 whip setae; dactylus distally with 5 whip setae.

PVI (Fig. 7 C) basis dorsal margin proximally with 4 short whip setae, medially with 1 seta, broken, missing, distally with 2 robust whip setae; ventral margin distally with 1 whip seta; distal margin anteriorly with 1 whip seta; ischium dorsal margin proximally and distally with 1 simple seta, respectively; ventral margin with 3 whip setae; distal margin with 1 short whip seta anteriorly and posteriorly, respectively; merus dorsal margin distally with 1 long whip seta, medially submarginally with 1 simple seta; ventral margin proximally with 1 whip seta, distally with 1 simple seta, medially submarginally with 1 simple seta; distal margin with 1 whip seta anteriorly and 1 UB seta posteriorly; carpus dorsal margin medially with 2 broken setae, missing and 1 whip seta, distally with 3 whip setae and 1 broom seta; ventral margin with 4 robust UB setae, submarginally with 2 short whip setae; distal margin posteriorly with 1 simple seta; propodus dorsal margin with 3 simple setae, 2 long simple setae, 1 broom seta, 2 broken setae (missing), mesially with 4 simple setae, distodorsally with 1 robust UB seta, 1 broom seta; ventral margin with 1 simple seta, 4 robust UB setae, dactylus distally with 5 whip setae.

PVII (Fig. 8 A and B) basis distodorsally with 1 short whip seta; proximoventrally with 1 simple seta and distoventrally with 1 short whip seta; ischium dorsal margin with 3 whip setae, submarginally with 1 short simple seta; ventral margin with 2 simple setae; merus dorsal margin medially with 1 short whip seta, distally with 1 long simple seta; ventral margin proximally with 1 whip seta, medially submarginally with 1 simple seta, distally with 2 long whip setae; distal margin anteriorly with 1 whip seta; carpus dorsal margin with medially with 2 whip setae, distally with 1 broom seta, 2 simple setae, 1 UB seta, 2 broken setae (missing), ventral margin with 4 robust UB setae, submarginally with 3 whip setae; propodus dorsal margin medially with 2 broken setae (missing), distally with 4 long whip setae and 1 broom seta, on right PVII with 1 UB seta; ventral margin with 4 robust UB setae, submarginally with 5 whip setae; dactylus distally with 5 whip setae.

PlpI (Fig. 9 B, Fig. 10 A and B) length 2.1 width, proximally widest, with shallow lateral notch distally of proximal third, progressively narrower from notch to apex; distolateral lobes narrow, pointed and pointing caudolaterally, laterally with 3–4 long, simple setae; distomedial lobes slightly shorter and wider, apex broadly rounded, distal margin with 4 simple setae. PlpII (Fig. 9 C and Fig. 10 C) length 1.7 width, basis lateral margin mid- 1 / 3 convex, apex narrowly rounded. Lateral margin with row of simple setae, distolateral with row of pappose setae, apex with 2 long, simple setae. Exopod asetose, length approx. 2 width, articulating at approx. 2 / 3 of the length of the basipodite. Endopod inserting at mid-length of basis, stylet longer than body length, distal end whip-like, coiled at least 10 times. PlpIII (Fig. 9 D and Fig. 10 D) exopod longer than endopod, distal end wide, rounded, lateral and distomesial margin densely setose, apex with 6 plumose setae; endopod distally with 7 plumose setae. PlpIV (Fig. 9 D) exopod length and width about 0.5 endopod length and width respectively, asetose.

Urp (Figs 2 , 9 , 10 ) 0.33 body length, 0.96 Plt length, protopod and rami cylindrical, protopod length 8.3 width, with 6–10 simple setae scattered across article and 3 robust setae on mesial margin; endopod length 1.1 protopod length, caudally pointing parallel to longitudinal body axis, with 8–9 simple setae; endopod length 1.9 exopod length, pointing caudolaterally at an angle of ca. 45 degrees from longitudinal axis, distally with 4–5 simple setae.

Diagnosis

Body elongate, widest at pereonite 1. Cephalothorax rostrum bulge-shaped; eyes reduced; preocular spine pointed anterolaterally, posterolateral margin serrated. Pereonites 1–2 and 5–7 lateral projection single; pereonites 3–4 lateral projections bifid; pereonites 1–2 projections posterolateral margin serrated, pereonites 5–7 projections anterolateral margin serrated; pereonites 3–4 lateral projections anterolaterally and posterolaterally serrated; pereonites sternal spines present. Pleotelson proximal quarter narrow, gradually wider towards posterior, lateral margins in medial 2 / 4 concave, distal quarter narrow, tapering lateral margins convex with 4 spine-like setae on each side; posterior apex protruding. Antenna flagellomere 1 length similar to combined length of remaining 11–12 flagellomeres. Mandibular palp absent. Pleopods I lateral lobes projecting beyond medial lobes; apices pointed laterally. Uropods articulated at posterolateral pleotelson margin, extending beyond pleotelson apex; posterolateral margin concave at insertion of uropods. Uropod endopod length subsimilar protopod length, exopod length 0.50 endopod length.

Etymology

The name “ maletensis ” is related to the geographic location of the type locality in Malta. According to one theory about the etymology of “ Malta ”, the name is derived from the Phoenician “ malet ” (also spelled “ maleth ”) and means “ place of refuge ”, “ haven ” or “ port ”. So, “ Mexicope maletensis ” translates into “ Maltese Mexicope ” or “ Mexicope from Malta ”.

Distribution

Only known from type locality. The known depth distribution of the genus Mexicope is extended, based on the newly-presented record. Previously ranging from 2 m to 80 m depth, Mexicope now has been reported from 2 m to 120 m depth. Furthermore, the distribution of the family Acanthaspidiidae is extended to include the Mediterranean Sea.

Taxon discussion

A comparisons between the species of Mexicope were based on male specimens, because only a single male specimen of Mexicope maletensis sp. nov. was available for this study. While similarities to some congeners are evident in various characters, M. maletensis sp. nov. shows a unique combination of morphological features rendering this species overall distinct.

The assignment of the new species to the Acanthaspidiidae is based on typical family characters, such as the pointed body outline, single lateral projections on pereonites 1 and 5–7, bifid lateral projections on pereonites 3–4, antenna with a long flagellum and article 3 with exopod and cylindrical uropods ( Wägele 1989, Brandt 1991, Just 2001).

Similarities between M. westralia and M. maletensis sp. nov. are: Ceph inter-antennal margin (frons) curved anteriorly; Prn dorsally with robust setae, Prn 3–4 lateral projections bifid, subequal in length, Prn 6–7 mid-sternal spine present; Plt margins finely serrate, anteriorly to Urp insertion concave, finely serrate; AII peduncle article 6 slightly longer than 5; left Md with 6 denticulate spine-like setae, molar strongly tapering; PlpI proximal 1 / 3 broadest, abruptly narrowing, slightly tapering towards apex; PlpII basis lateral margin mid- 1 / 3 broadly convex with fringe of long slender setae, distal 1 / 3 concavely tapering to blunt point, endopod stylet long, whip-like, coiled extension; PlpIII exopod distal margin with 6 plumose setae; PlpIV exopod about half length of endopod, slender, naked; uropods about as long as Plt.

Mexicope maletensis sp. nov. differs from M. westralia as follows: Ceph rostrum present (absent), Prn mid-sternal spine present (presence on Prn 5–7 only), Prn 2 lateral projection single (bifid), Plt proximal quarter narrow, lateral margin convex, becoming wider, lateral margins medial 1 / 2 concave, distal quarter narrowly tapering, lateral margins convex (widening distally, in proximal 1 / 3 with faintly concave margins, middle 1 / 3 broadly convex), Plt apical lobe twice as long as wide (half as long as wide), AII flagellum article 1 conjoint, length as long as remaining 13 short articles (half-length of 14 short articles), Md palp absent (present), right Md with 6 denticulate spine-like setae, length progressively increasing, distal to proximal denticles number increasing (with 8 such setae), MxI outer lobe with 13 spines (12 denticulate spine-like setae), Mxp basis length 1.5 width (2.5 width), PlpI dorsally without setules, without tabs (dorsal mid-surface with field of setules, more distally with 2 triangular locking tabs), PlpIII endopod with 7 plumose setae (with 6 plumose setae), Urp outer ramus length 0.50 protopod length (exopod and protopod of similar length), exopod length ca. 0.50 endopod length (ca. 0.80).

Similarities between M. sushara and M. maletensis sp. nov. are: body length 2.0 width; inter-antennal margin (frons) more or less convex, rostral spine short, pre-ocular spines prominent, eyes laterally, stalked; Prn 1 anterolateral projections acute, curved towards anteriorly, Prn 3–4 lateral margins distinctly bifid, projections subequal in size, Prn 5–6 lateral projections directed posteriorly, Prn 2–3 and Prn 6–7 projections with anteriorly directed long dorsal setae, Prn 4 setae only on posterior lobe; Prn 7 mid-sternal spine present; AII flagellum conjoint article 1 length subequal length of remaining 12 articles; left Md lacinia mobilis with 4 cusps, molar tapering; MxII lateral and middle lobes each with 2 long and 2 short strongly serrate setae; Mxp epipodite linguiform; pereopods similar in shape, setation subequal, PI – III proportionally shorter than PIV – VII, length differences mostly caused by length variation of propodus; PlpI proximally widest, lateral margin narrowing abruptly, tapering smoothly to bilobed apex; PlpII lateral margin medially strongly convex, with dense row of simple setae, distolateral margin concave, endopod stylet long, distally coiled; PlpIII exopod distal margin with 6 plumose setae, exopod lateral margin with continuous fringe of setae; PlpIV exopod half as long as endopod, apically acute.

Mexicope maletensis sp. nov. differs from M. sushara as follows: Ceph rostral projection blunt, barely projecting (rostrum acute, projecting and curved upwards); Plt anterior quarter narrow, lateral margin convex, becoming wider posteriorly, lateral margins medially concave, distally narrowly tapering, convex (proximally narrow, widening abruptly); Prn 2 lateral projection single (bifid); AII article 6 distodorsal triangular lobe absent (present), Md incisors with 5 cusps (with 4 cusps), right and left Md with 6 denticulate spine-like setae, length and number of denticles progressively increasing from distal to proximal (left spine row of 5 denticulate spine-like setae, 8 simple setae; right spine row with 8 denticulate spine-like setae), palp absent (present); Mxp basis length 1.5 width (2.1 width); PlpI length 2.1 width (3.9 width); PlpII length 1.7 width (2.6 width), apex with 3 long simple setae (with 6 long plumose setae), exopod apex unilobed (bilobed); PlpIII endopod distal margin with 7 plumose setae (with 6 plumose setae).

Similarities between M. kensleyi and the new species are: preocular spines orientated anterolaterally; eyes on stalks; Prns laterally with few setae; AI heavily setose, flagellum with 13 articles, first article longest; Md palp absent, molar process conical setiferous, left lacinia quadridentate, one distal simple spine; MxI inner ramus shorter than outer one; Mxp palp 5 - segmented, segment width subequal, distal segment setose, endite broad, outer margin rounded, inner margin 2 coupling hooks, distal third with numerous setules, epipodite short, apically narrowly rounded; P propodus longest segment, merus bulbous, dactylus with two claws; PVII longest; PlpI laterally setose; PlpII protopod outer margin with long and short setae, endopod exceeding length of protopod, distally coiled; Urp elongate, biramous, peduncle length similar exopod length.

Mexicope maletensis sp. nov. differs from M. kensleyi as follows: body length almost 2.0 width (length almost 3.0 width), eyes ventrolaterally (dorsolaterally), Prn 1 widest (Prn 3 and 4 widest); left Md distally with 5 dentate spines (with 6 spines); PlpII endopod distally coiled at least 10 times (stylet coiled once).

Notes

The initial difficulties we had in assigning the new species to a genus are emblematic of the currently inadequate and vague diagnoses of all three genera of Acanthaspidiidae (see also Timm et al. (2013)). With previously only three known species for the genus Mexicope , it is no surprise that, for each new species, a modification of the generic diagnoses was necessary and the discrimination amongst the acanthaspidiid genera was partially blurry. This development is particularly evident in Ianthopsis (see taxon discussion for Ianthosis below).

A new diagnosis for Mexicope is presented here because previous diagnoses of the genera Ianthopsis and Mexicope ( Just 2001, Bruce 2004) show significant overlap between Ianthopsis and Mexicope in some character states leading to difficulties to differentiate between these genera and to classify the new species described here. Character states that support the classification of the new species as either Ianthopsis or Mexicope are the absence of dorsal tubercles on the cephalothorax, the presence of eyes on eyestalks, single lateral projections on pereonite 1, the absence of tergal spines or humps, a fringe of long setae laterally on the second pleopod basis which are longest apically, finely serrated pleotelson margins and uropod rami that are at least as long as the peduncle. The presence of a simple, bulge-shaped rostrum, the antennula length of 0.25 times antenna length, the absence of a triangular lobe on antenna article 6 and the short, curved, robust setae on the pleotelson on the one hand speak for a classification of the new species as Ianthopsis according to the previous diagnosis. The classification of the new species as Mexicope , on the other hand, is supported by the presence of a pre-ocular spine, rows of elongate, simple setae on the posterolateral projections of pereonites 2–4 and 6–7, the presence of a sternal spine on pereonite 7, prognathous mouthparts, a strongly tapering, pointed mandibular molar with long apical setae, the lack of a mandibular palp, a short maxilliped epipod reaching only half way between the coxo-basal articulation and the palp articulation, a coiled pleopod II stylet and uropods that are as long as the pleotelson. In summary, over ten, partially complex characters suggest the classification as Mexicope as opposed to only four, relatively weak characters in favour of Ianthopsis (see Table 1 ).

Figures

Figure 2. Mexicope maletensis sp. nov. male holotype (SMF 62000), digitised pencil drawings of habitus: A habitus lateral; B habitus dorsal; Scale bar = 1 mm.

Figure 3. Mexicope maletensis sp. nov. male holotype (SMF 62000), digitised pencil drawings of antennula and antenna: A antenna; B antennula, in situ. Scale bar = 0.5 mm.

Figure 4. Mexicope maletensis sp. nov. male holotype (SMF 62000), digitised pencil drawings of mouthparts: A left and right mandibles left maxilliped, dorsal aspect; B maxillula; C maxilla; D right mandible; E right maxilliped, ventral aspect. Scale bar = 250 µm.

Figure 5. Mexicope maletensis sp. nov. male holotype (SMF 62000), confocal laser scanning microscopy (cLSM) images of mouthparts: A left maxilliped, dorsal aspect; B right maxilliped, ventral aspect; A left mandible; B right mandible; C maxilla; D maxillula. Scale bar = 250 µm.

Figure 6. Mexicope maletensis sp. nov. male holotype (SMF 62000), digitised pencil drawings of anterior pereopods in lateral view: A pereopod I; B pereopod II; C pereopod III. Scale bar = 250 µm.

Figure 7. Mexicope maletensis sp. nov. male holotype (SMF 62000), digitised pencil drawings of posterior pereopods in lateral view: A pereopod IV; B pereopod V; C pereopod VI. Scale bar 250 µm.

Figure 8. Mexicope maletensis sp. nov. male holotype (SMF 62000), digitised pencil drawings of seventh pereopods in lateral view: A right pereopod VII; B left pereopod VII; C simple (asetulate) seta; D whip seta; E robust seta; F unequally bifid (sensillate) seta; G broom seta (distal half of shaft setulate, pappose); H broom seta (apically setulate, pappose); I simple sensilla (shaft subcylindrical, tip rounded); J fringed sensilla (shaft subcylindrical, distally densely covered by small scales, tip rounded). Scale bar (A – B) = 250 µm (C – I not to scale).

Figure 9. Mexicope maletensis sp. nov. male holotype (SMF 62000), digitised pencil drawings pleopods: A pleotelson in ventral view, uropodal setae omitted; B pleopod I; C pleopods III and IV (underneath); D pleopod II. Scale bar = 250 µm.

Figure 10. Mexicope maletensis sp. nov. male holotype (SMF 62000), confocal laser scanning microscopy (cLSM) images of pleopods: A pleotelson in ventral view; B pleopod I; C pleopod II; D pleopod III and IV. Scale bar = 250 µm.